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Tag: Body fat

  • What Is the Role of Our Genes in the Obesity Epidemic?  | NutritionFacts.org

    What Is the Role of Our Genes in the Obesity Epidemic?  | NutritionFacts.org

    The “fat gene” accounts for less than 1 percent of the differences in size between people.

    To date, about a hundred genetic markers have been linked to obesity, but when you put them all together, overall, they account for less than 3 percent of the difference in body mass index (BMI) between people. You may have heard about the “fat gene,” called FTO, short for FaT mass and Obesity-associated). It’s the gene most strongly linked to obesity, but it explains less than 1 percent of the difference in BMI between people, a mere 0.34 percent. 

    As I discuss in my video The Role of Genes in the Obesity Epidemic, FTO codes for a brain protein that appears to affect our appetite. Are you one of the billion people who carry the FTO susceptibility genes? It doesn’t matter because it only appears to result in a difference in intake of a few hundred extra calories a year. The energy imbalance that led to the obesity epidemic is on the order of hundreds of calories a day, and that’s the gene known so far to have the most effect. The chances of accurately predicting obesity risk based on FTO status is “only slightly better than tossing a coin.” In other words, no, those genes don’t make you look fat.

    When it comes to obesity, the power of our genes is nothing compared to the power of our fork. Even the small influence the FTO gene does have appears to be weaker among those who are physically active and may be abolished completely in those eating healthier diets. FTO only appears to affect those eating diets higher in saturated fat, which is predominantly found in meat, dairy, and junk food. Those eating more healthfully appear to be at no greater risk of weight gain, even if they inherited the “fat gene” from both of their parents.

    Physiologically, FTO gene status does not appear to affect our ability to lose weight. Psychologically, knowing we’re at increased genetic risk for obesity may motivate some people to eat and live more healthfully, but it may cause others to fatalistically throw their hands up in the air and resign themselves to thinking that it just runs in their family, as you can see in the graph below and at 2:11 in my video. Obesity does tend to run in families, but so do lousy diets. 

    Comparing the weight of biological versus adopted children can help tease out the contributions of lifestyles versus genetics. Children growing up with two overweight biological parents were found to be 27 percent more likely to be overweight themselves, whereas adopted children placed in a home with two overweight parents were 21 percent more likely to be overweight. So, genetics do play a role, but this suggests that it’s more the children’s environment than their DNA.

    One of the most dramatic examples of the power of diet over DNA comes from the Pima Indians of Arizona. As you can see in the graph below and at 3:05 in my video, they not only have among the highest rates of obesity, but they also have the highest rates of diabetes in the world. This has been ascribed to their relatively fuel-efficient genetic makeup. Their propensity to store calories may have served them well in times of scarcity when they were living off of corn, beans, and squash, but when the area became “settled,” their source of water, the Gila River, was diverted upstream. Those who survived the ensuing famine had to abandon their traditional diet to live off of government food programs and chronic disease rates skyrocketed. Same genes, but different diet, different result. 

    In fact, a natural experiment was set up. The Pima living over the border in Mexico come from the same genetic pool but were able to maintain more of their traditional lifestyle, sticking with their main staples of beans, wheat flour tortillas, and potatoes. Same genes, but seven times less obesity and about four times less diabetes. You can see those graphs below and at 3:58 and 4:02 in my video. Genes may load the gun, but diet pulls the trigger.

    Of course, it’s not our genes! Our genes didn’t suddenly change 40 years ago. At the same time, though, in a certain sense, it could be thought of as all in our genes. That’s the topic of my next video The Thrifty Gene Theory: Survival of the Fattest.

    This is the second in an 11-video series on the obesity epidemic. If you missed the first one, check out The Role of Diet vs. Exercise in the Obesity Epidemic. 

    Michael Greger M.D. FACLM

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  • The Roles Diet and Exercise Play in the Obesity Epidemic  | NutritionFacts.org

    The Roles Diet and Exercise Play in the Obesity Epidemic  | NutritionFacts.org

    The common explanations for the cause of the obesity epidemic put forward by the food industry and policymakers, such as inactivity or a lack of willpower, are not only wrong, but actively harmful fallacies.

    Obesity isn’t new, but the obesity epidemic is. We went from a few corpulent kings and queens, like Henry VIII or Louis VI (known as Louis le Gros, or “Louis the Fat”), to a pandemic of obesity, now considered to be “arguably the gravest and most poorly controlled public health threat of our time.” As you can see below and at 0:34 in my video The Role of Diet vs. Exercise in the Obesity Epidemic, about 37 percent of American men are obese and 41 percent of American women, with no end in sight. Earlier reports had suggested that the rise in obesity was at least slowing down, but even that doesn’t appear to be the case. Similarly, we had thought we were turning the corner on childhood obesity “[a]fter 35 years of unremittingly bad news,” but the bad news continues. Childhood and adolescent obesity rates have continued to rise, now into the fourth decade. 

    Over the last century, obesity appears to have jumped ten-fold, from about 1 in 30 to now 1 in 3, but it wasn’t a steady rise. As you can see in the graph below and at 1:15 in my video, something seems to have happened around the late 1970s—and not just in the United States, but around the globe. The obesity pandemic took off at about the same time in the 1970s and 1980s in most high-income countries. The fact that the rapid rise “seemed to begin almost concurrently” across the industrialized world suggests a common cause. What might that trigger have been? 

    Any potential driver would have to be global and “coincide with the upswing of the epidemic.” So, the change would have had to have started about 40 years ago and would have had to have been able to spread rapidly around the globe. Let’s see how all the various theories stack up. For example, as you can see below and at 1:55 in my video, some have blamed changes in our built environment and shifts in city planning that have made our communities less conducive to walking, biking, and grocery shopping. That doesn’t meet our criteria for a credible cause, though, because there was no universal, simultaneous change in our neighborhoods within that time frame.

    When researchers surveyed hundreds of policymakers, most blamed the obesity epidemic on a “lack of personal motivation.” Do you see how little sense that makes? In the United States, for example, obesity shot up across the entire population in the late 1970s, as you can see at 2:26 in my video. I concur with the researchers who “believe it is implausible that each age, sex, and ethnic group, with massive differences in life experience and attitudes, had a simultaneous decline in willpower related to healthy nutrition or exercise.” More plausible than a global change like our characters would be some global change like our lives. 

    The food industry blames inactivity. “If all consumers exercised,” said the CEO of PepsiCo, “obesity wouldn’t exist.” Coca-Cola went a step further, spending $1.5 million to create the Global Energy Balance Network to downplay the role of diet. Leaked emails show the company planned on using the front to “serve as a ‘weapon’ to ‘change the conversation’ about obesity in its ‘war’ with public health.

    This tactic is so common among food and beverage companies that it even has a name: “leanwashing.” You’ve heard of greenwashing, where companies deceptively pretend to be environmentally friendly. Leanwashing is the term used to describe companies that try to position themselves as helping to solve the obesity crisis when they’re instead directly contributing to it. For example, the largest food company in the world, Nestlé, has “rebranded itself as the ‘world’s leading nutrition, health and wellness company.” Yes, that Nestlé, makers of Nesquik, Cookie Crisp, and historically more than a hundred different brands of candy, including Butterfinger, Kit Kat, Goobers, Gobstoppers, Runts, and Nerds. Another one of its slogans is “Good Food, Good Life.” Its Raisinets may have some fruit, but Nestlé seems to me more Willy Wonka than wellness. 

    The constant corporate drumbeat of overemphasis on physical inactivity appears to be working. In response to the Harris poll question, “Which of these do you think are the major reasons why obesity has increased?,” a “huge majority of 83% chose lack of exercise, while only 34% chose excessive calorie consumption.” “Confusion about the effect of exercise on the energy balance” has been identified as one of the most common misconceptions about obesity. The scientific community has “come to a fairly decisive conclusion” that the factors governing calorie intake more powerfully affect overall calorie balance. It’s our fast food more than our slow motion. 

    “There is considerable debate in the literature today about whether physical activity has any role whatsoever in the epidemic of obesity that has swept the globe since the 1980s.” The increase in caloric intake per person is more than enough to explain the obesity epidemic in the United States and also explain it globally. If anything, the level of physical activity over the last few decades has gone up slightly in both Europe and North America. Ironically, this may be a result of the extra energy it takes to move around our heavier bodies, making it a consequence of the obesity problem rather than the cause.

    “Formal exercise plays a very small role in the total daily physical activity energy expenditure.” Think how much more physical work people used to do in the workplace, on the farm, or even in the home. It’s not just the shift in collar color from blue to white. Increasing automation, computerization, mechanization, motorization, and urbanization have all contributed to increasingly more sedentary lifestyles over the last century—and that’s the problem with the theory. The occupational shifts and advent of labor-saving devices “have been gradual and largely predated the dramatic increase in weight gain across the developed world in the past few decades.” Washing machines, vacuum cleaners, and the Model T were all invented before 1910. Indeed, when put to the test using state-of-the-art methods to measure energy in and energy out, it was caloric intake, not physical activity, that predicted weight gain over time. 

    The common misconception that obesity is mostly due to lack of exercise may not just be a benign fallacy. Personal theories of causation appear to impact people’s weight. Those who blame insufficient exercise are significantly more likely to be overweight than those who implicate a poor diet. Put those who believe lack of exercise causes obesity in a room with chocolate, and they can covertly be observed consuming more candy. Those holding that view may be different in other ways, though. You can’t prove cause and effect until you put it to the test. And, indeed, as you can see in the graph below, and at 7:22 in my video, people randomized to read an article implicating inactivity went on to eat significantly more sweets than those reading about research that indicated diet. A similar study found that those presented with research blaming genetics subsequently ate significantly more cookies. The title of that paper? “An Unintended Way in Which the Fat Gene Might Make You Fat.” 

    When I sat down to write How Not to Diet, I knew this “what triggered the obesity epidemic” was going to be a big question I had to face. Was it inactivity (just kids sitting around playing video games or scrolling on their phones)? Was it genetic? Was it epigenetic (something turning on our fat genes)? Or was it just the food? Were we eating more fat all of a sudden? More carbs? More processed foods? Or were we just eating more period, because of bigger serving sizes or more snacking? Inquiring minds wanted to know. 

    This is the first in an 11-video series to answer this question, which I originally released in a two-hour webinar in 2020. Check out the webinar digital download here. Or, check them out in the related posts below.  

    Michael Greger M.D. FACLM

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  • Seasonal Weight Gain in the Fall  | NutritionFacts.org

    Seasonal Weight Gain in the Fall  | NutritionFacts.org

    SAD doesn’t just stand for the standard American diet.

    There’s a condition known as seasonal affective disorder that is characterized by increased appetite and cravings, as well as greater sleepiness and lethargy, that begins in autumn when light exposure starts to dwindle. This now appears to represent the far end of a normal spectrum of human behavior. We appear to eat more as the days get shorter. There is a “marked seasonal rhythm” to calorie intake with greater meal size, eating rate, hunger, and overall calorie intake in the fall. 

    In preparation for winter, some animals hibernate, doubling their fat stores with autumnal abundance to deal with the subsequent scarcity of winter. Genes have been identified in humans that are similar to hibernation genes, which may help explain why we exhibit some of the same behaviors, and the autumn effect isn’t subtle. As you can see in the graph below and at 1:06 in my video Friday Favorites: Why People Gain Weight in the Fall, researchers calculated a 222-calorie difference between how many calories we consume in the fall versus the spring. This isn’t just because it’s colder, either, since we eat more in the fall than in the winter. It appears we’re just genetically programmed to prep for the deprivation of winter that no longer comes. 

    It’s remarkable that, in this day and age of modern lighting and heating, our bodies would still pick up enough environmental cues of the changing seasons to have such a major influence on our eating patterns. Unsurprisingly, bright light therapy is used to treat seasonal affective disorder, nearly tripling the likelihood of remission, compared to placebo. Though it’s never been tested directly, it can’t hurt to take the dog out for some extra morning and daytime walks in the fall to try to fend off some of the coming holiday season weight gain.

    People blame the holidays for overeating, but it may be that “rather than the holidays causing heightened intake, the seasonal heightening of intake in the fall may have caused the scheduling of holidays at that time.”

    Regardless, as you can see below and at 2:15 in my video, other “specific recommendations for the prevention of obesity and metabolic syndrome by improving the circadian system health,” based on varying degrees of evidence, include: sleeping during the night and being active during the day; sleeping enough—at least seven or eight hours a night; early to bed, early to rise; and short naps are fine. (Contrary to popular belief, daytime napping does not appear to adversely impact sleep at night.) Also recommended: avoiding bright light exposure at night; sleeping in total darkness when possible; making breakfast or lunch your biggest meal of the day; not eating or exercising right before bed; and completely avoiding eating at night. 

    This was the last video in my chronobiology series. If you missed any of the others, check out the related posts below.

    Michael Greger M.D. FACLM

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  • Phototherapy and Losing Weight  | NutritionFacts.org

    Phototherapy and Losing Weight  | NutritionFacts.org

    What did randomized controlled trials of phototherapy—bright morning light—for weight loss find? 

    If weakening our circadian rhythm can cause weight gain, might strengthening it facilitate weight loss? You may remember the child’s swing analogy I shared previously. Regular morning meals can give our cycles a little daily push, but the biggest shove comes from our exposure to bright morning light. Similarly, exposure to light at night could be analogous to nighttime eating, as you can see below and at 0:31 in my video Shedding Light on Shedding Weight. 

    Of course, we’ve had candles to illuminate our nights for 5,000 years, but flames from candles, campfires, and oil lamps are “strongly skewed towards the red end of the [light] spectrum; as a result, firelight has much less impact on circadian rhythmicity than electric light.” It’s the shorter blue wavelengths that specially set our circadian clocks. Electric lighting, which we’ve only had for a little over a century, “has gradually changed since the 1960s from an incandescent-bulb form consisting of mainly low-level yellow wavelengths to high-intensity discharge forms,” such as fluorescents and LED lights, “that contain blue wavelengths,” which are more similar to morning sunlight and have the strongest effect on our circadian rhythm.

    Using wrist meters to measure ambient light exposure, researchers found that increased exposure to light in the evening and nighttime correlated with a subsequent increased risk of developing obesity over time. This was presumed to be due to circadian misalignment, but might it instead be a sign of not sleeping as much, and maybe that’s the real reason people grew heavier? This was controlled for in a study of more than 100,000 women, which found that the odds of obesity trended with higher nighttime light exposure independent of sleep duration.

    Compared to women who reported their bedrooms at night were either too dark to see their hand in front of their face or at least dark enough that they couldn’t see across the room, those who reported their bedrooms were light enough to see across the room were significantly heavier. They weren’t all sleeping with nightlights on either. Without blackout curtains on windows, many neighborhoods may be bright enough to cause circadian disruption. Using satellite imagery, scientists have even been able to correlate higher obesity rates with brighter communities. There’s so much light at night these days that, outside of a blackout, the only Milky Way our children will likely ever see is inside a candy wrapper.

    Although sleep quantity could be controlled, what about sleep quality? Maybe people sleeping in bedrooms that aren’t as dim don’t sleep as soundly, leaving them too tired to exercise the next day, for example. You can’t know for sure if nocturnal light exposure is harmful in and of itself until you put it to the test. When that was done, those randomized to exposure to bright light for a few hours in the evenings or exposed even just for a single night suffered adverse metabolic consequences. 

    The more intriguing question then becomes: Can circadian syncing with morning bright light therapy be a viable weight-loss strategy? Insufficient morning light may be the circadian equivalent of skipping breakfast. Indoor lighting is too bright at night, but it may be too dim during the day to robustly boost our daily rhythm. Light exposure from getting outdoors in the morning, even on an overcast day, is correlated to lower body weight compared to typical office lighting, so some doctors started trying “phototherapy” to treat obesity. The first case reports began being published in the 1990s. Three out of four women lost an average of about four pounds over six weeks of morning bright light exposure, but there was no control group to confirm the effect. 

    Ten years later, the first randomized controlled trial was published. Overweight individuals were randomized to an exercise intervention with or without an hour a day of bright morning light. Compared to normal indoor lighting, the bright light group lost more body fat, but it’s possible the light just stimulated them to exercise harder. Studies show that exposure to bright light, even the day prior to exercise, may boost performance. In a handgrip endurance test, exposure to hours of bright light increased the number of contractions until exhaustion from about 770 to 860 the next day. While light-induced improvements in activity or mood can be helpful in their own right, it would be years later still before we finally learned whether the light exposure itself could boost weight loss. 

    Following an unpublished study in Norway purporting to show a dozen-pound weight-loss advantage to eight weeks of 30 minutes of daily daylight (compared to indoor lighting), researchers tried three weeks of 45 minutes of morning bright light compared to the same time sitting in front of an “ion generator” that appeared to turn on but was secretly deactivated. As you can see in the graph below and at 5:08 in my video, the three weeks of light beat out the placebo, but the average difference in body fat reduction was only about a pound. This slight edge didn’t seem to correlate with mood changes, but bright light alone can stimulate serotonin production in the human brain and cause the release of adrenaline-type hormones, both of which could benefit body fat aside from any circadian effects. 

    Regardless of the mechanism, bright morning daylight exposure could present a novel weight-loss strategy straight out of the clear blue sky.  

    I have a whole series on chronobiology. You can see all of the videos on the topic page. The last few are listed below in the related posts and help to paint the full picture of how our environment can affect our circadian rhythms.

    For more on weight loss, you can also check out my recent series in the related posts below, or browse all of my weight loss videos here. 

    Michael Greger M.D. FACLM

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  • Irregular Meals, Night Shifts, and Metabolic Harms  | NutritionFacts.org

    Irregular Meals, Night Shifts, and Metabolic Harms  | NutritionFacts.org

    What can shift workers do to moderate the adverse effects of circadian rhythm disruption?

    Shift workers may have higher rates of death from heart disease, stroke, diabetes, dementia, and cardiovascular disease, as well as higher rates of death from cancer. Graveyard shift, indeed! But, is it just because they’re eating out of vending machines or not getting enough sleep? Highly controlled studies have recently attempted to tease out these other factors by putting people on the same diets with the same sleep—but at the wrong time of day. Redistributing eating to the nighttime resulted in elevated cholesterol and increases in blood pressure and inflammation. No wonder shift workers are at higher risk. Shifting meals to the night in a simulated night-shift protocol effectively turned about one-third of the subjects prediabetic in just ten days. Our bodies just weren’t designed to handle food at night, as I discuss in my video The Metabolic Harms of Night Shifts and Irregular Meals.

    Just as avoiding bright light at night can prevent circadian misalignment, so can avoiding night eating. We may have no control over the lighting at our workplace, but we can try to minimize overnight food intake, which has been shown to help limit the negative metabolic consequences of shift work. When we finally do get home in the morning, though, we may disproportionately crave unhealthy foods. In one experiment, 81 percent of participants in a night-shift scenario chose high-fat foods, such as croissants, out of a breakfast buffet, compared to just 43 percent of the same subjects during a control period on a normal schedule.

    Shiftwork may also leave people too fatigued to exercise. But, even at the same physical activity levels, chronodisruption can affect energy expenditure. Researchers found that we burn 12 to 16 percent fewer calories while sleeping during the daytime compared to nighttime. Just a single improperly-timed snack can affect how much fat we burn every day. Study subjects eating a specified snack at 10:00 am burned about 6 more grams of fat from their body than on the days they ate the same snack at 11:00 pm. That’s only about a pat and a half of butter’s worth of fat, but it was the identical snack, just given at a different time. The late snack group also suffered about a 9 percent bump in their LDL cholesterol within just two weeks.

    Even just sleeping in on the weekends may mess up our metabolism. “Social jetlag is a measure of the discrepancy in sleep timing between our work days and free days.” From a circadian rhythm standpoint, if we go to bed late and sleep in on the weekends, it’s as if we flew a few time zones west on Friday evening, then flew back Monday morning. Travel-induced jet lag goes away in a few days, but what might the consequences be of constantly shifting our sleep schedule every week over our entire working career? Interventional studies have yet put it to the test, but population studies suggest that those who have at least an hour of social jet lag a week (which may describe more than two-thirds of people) have twice the odds of being overweight. 

    If sleep regularity is important, what about meal regularity? “The importance of eating regularly was highlighted early by Hippocrates (460–377 BC) and later by Florence Nightingale,” but it wasn’t put to the test until the 21st century. A few population studies had suggested that those eating meals irregularly were at a metabolic disadvantage, but the first interventional studies weren’t published until 2004. Subjects were randomized to eat their regular diets divided into six regular eating occasions a day or three to nine daily occasions in an irregular manner. Researchers found that an irregular eating pattern can cause a drop in insulin sensitivity and a rise in cholesterol levels, as well as reduce the calorie burn immediately after meals in both lean and obese individuals. The study participants ended up eating more, though, on the irregular meals, so it’s difficult to disentangle the circadian effects. The fact that overweight individuals may overeat on an irregular pattern may be telling in and of itself, but it would be nice to see such a study repeated using identical diets to see if irregularity itself has metabolic effects.

    Just such a study was published in 2016: During two periods, people were randomized to eat identical foods in a regular or irregular meal pattern. As you can see in the graph below and at 4:47 in my video, during the irregular period, people had impaired glucose tolerance, meaning higher blood sugar responses to the same food.

    They also had lower diet-induced thermogenesis, meaning the burning of fewer calories to process each meal, as seen in the graph below and at 4:55 in my video.

    The difference in thermogenesis only came out to be about ten calories per meal, though, and there was no difference in weight changes over the two-week periods. However, diet-induced thermogenesis can act as “a satiety signal.” The extra work put into processing a meal can help slake one’s appetite. And, indeed, “lower hunger and higher fullness ratings” during the regular meal period could potentially translate into better weight control over the long term. 

    The series on chronobiology is winding down with just two videos left in this series: Shedding Light on Shedding Weight and Friday Favorites: Why People Gain Weight in the Fall.

    If you missed any of the other videos, see the related posts below. 
     

    Michael Greger M.D. FACLM

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  • Syncing Your Brain and Body Clocks  | NutritionFacts.org

    Syncing Your Brain and Body Clocks  | NutritionFacts.org

    Exposure to bright light synchronizes the central circadian clock in our brain, whereas proper meal timing helps sync the timing of different clock genes throughout the rest of our body. 
     
    One of the most important breakthroughs in recent years has been the discovery of “peripheral clocks.” We’ve known for decades about the central clock—the so-called suprachiasmatic nucleus. It sits in the middle of our brain right above the place where our optic nerves cross, allowing it to respond to day and night. Now we also know there are semi-autonomous clocks in nearly every organ of our body. Our heart runs on a clock, our lungs run on one, and so do our kidneys, for instance. In fact, up to 80 percent of the genes in our liver are expressed in a circadian rhythm.

    Our entire digestive tract is, too. The rate at which our stomach empties, the secretion of digestive enzymes, and the expression of transporters in our intestinal lining for absorbing sugar and fat all cycle around the clock. So, too, does the ability of our body fat to sop up extra calories. The way we know these cycles are driven by local clocks, rather than being controlled by our brain, is that you can take surgical biopsies of fat, put them in a petri dish, and watch them continue to rhythm away.

    All of this clock talk is not just biological curiosity. Our health may depend on keeping all of them in sync. “Imagine a child playing on a swing.” Picture yourself pushing, but you become distracted by what’s going on around you in the playground and stop paying attention to the timing of the push. So, you forget to push or you push too early or too late. What happens? Out of sync, the swinging becomes erratic, slows, or even stops. That is what happens when we travel across multiple time zones or have to work the night shift.

    The “pusher” in this case is the light cues falling onto our eyes. Our circadian rhythm is meant to get a “push” from bright light every morning at dawn, but if the sun rises at a different time or we’re exposed to bright light in the middle of the night, this can push our cycle out of sync and leave us feeling out of sorts. That’s an example of a mismatch between the external environment and our central clock. Problems can also arise from a misalignment between the central clock in our brain and all the other organ clocks throughout our body. An extreme illustration of this is a remarkable set of experiments suggesting that even our poop can get jet lag.

    As you can see below and at 2:31 in my video How to Sync Your Central Circadian Clock to Your Peripheral Clocks, our microbiome seems to have its own circadian rhythm.

    Even though the bacteria are down where the sun doesn’t shine, there’s a daily oscillation in both bacterial abundance and activity in our colon, as you can see in the graph below and at 2:43 in my video. Interesting, but who cares? We all should. 

    Check this out: If you put people on a plane and fly them halfway around the world, then feed their poop to mice, those mice grow fatter than mice fed preflight feces. The researchers suggest the fattening flora was a consequence of “circadian misalignment.” Indeed, several lines of evidence now implicate “chronodisruption”—the state in which our central and peripheral clocks diverge out of sync—as playing a role in conditions such as premature aging and cancer, as well as ranging to others like mood disorders and obesity.

    Exposure to bright light is the synchronizing swing pusher for our central clock. What drives our internal organ clocks that aren’t exposed to daylight? Food intake. That’s why the timing of our meals may be so important. Researchers removed all external timing cues by keeping study participants under constant dim light and found that you could effectively decouple central rhythms from peripheral ones just by shifting meal times. They took blood draws every hour and biopsies of the subjects’ fat every six hours to demonstrate the resulting metabolic disarray.

    Just as morning light can help sync the central clock in our brain, morning meals can help sync our peripheral clocks throughout the rest of our body. Skipping breakfast disrupts the normal expression and rhythm of these clock genes themselves, which coincides with adverse metabolic effects. Thankfully, they can be reversed. Take a group of habitual breakfast-skippers and have them eat three meals at 8:00 am, 1:00 pm, and 6:00 pm, and their cholesterol and triglycerides improve, compared to taking meals five hours later at 1:00 pm, 6:00 pm, and 11:00 pm. There is a circadian rhythm to cholesterol synthesis in the body, too, which is also “strongly influenced by food intake.” This is evidenced by the 95 percent drop in cholesterol production in response to a single day of fasting. That’s why a shift in meal timing of just a few hours can result in a 20-point drop in LDL cholesterol, thanks to eating earlier meals, as you can see below and at 5:00 in my video. 

    If light exposure and meal timing help keep everything synced, what happens when our circumstances prevent us from sticking to a normal daytime cycle? We’ll find out in The Metabolic Harms of Night Shifts and Irregular Meals. If you’re just coming into the series, be sure to check out the related posts below.  

    Michael Greger M.D. FACLM

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  • A Look at the 5:2 Diet and the Fasting-Mimicking Diet  | NutritionFacts.org

    A Look at the 5:2 Diet and the Fasting-Mimicking Diet  | NutritionFacts.org

    What are the effects of eating only five days a week or following a fasting-mimicking diet five days a month? 
     
    Instead of eating every other day, what if you ate five days a week and fasted for the other two? As I discuss in my video The 5:2 Diet and the Fasting-Mimicking Diet Put to the Test, the available data are similar to that of alternate-day fasting: About a dozen pounds of weight loss was reported in overweight men and also reported in overweight women over six months, with no difference found between participants on the 5:2 intermittent fasting regimen and those on a continuous 500-calories-a-day restriction. The largest trial to date found an 18-pound weight loss within six months in the 5:2 group, which isn’t significantly different from the 20 pounds lost in the continuous calorie restriction group. Weight maintenance over the subsequent six months was also found to be no different.
     
    Though feelings of hunger may be more pronounced on the 5:2 pattern than on an equivalent level of daily calorie cutting, it does not seem to lead to overeating on non-fasting days. One might expect going two days without food may negatively impact mood, but no such adverse impact was noted for those fully fasting on zero calories or sticking to just two packets of oatmeal on each of the “fasting” days. (The oatmeal provides about 500 calories a day.) Like alternate-day fasting, the 5:2 fasting pattern appeared to have inconsistent effects on cognition and on preserving lean mass, and it also failed to live up to the “popular notion” that intermittent fasting would be “easier” to adhere to than daily calorie restriction. 
     
    Compared to those in the continuous-restriction control group, fewer subjects in the 5:2 pattern group expressed interest in continuing their diet after the study was over. This was attributed to quality-of-life issues, with 5:2 fasting participants citing headaches, lack of energy, and difficulty fitting the fasting days into their weekly routine. However, as you can see below and at 1:53 in my video, there has yet to be a single 5:2 diet study showing elevated LDL cholesterol compared with continuous calorie restriction at six months. Nor has it been shown for a year. This offers a potential advantage over alternate-day regimens. 

    Instead of 5:2, what about 25:5, spending five consecutive days a month on a “fasting-mimicking diet” (FMD)? Longevity researcher Valter Longo designed a five-day meal plan to try to simulate the metabolic effects of fasting by being low in protein, sugars, and calories with zero animal protein and zero animal fat. By making the diet plant-based, he hoped to lower the level of the cancer-promoting growth hormone IGF-1. He indeed accomplished this goal, along with a drop in markers of inflammation, after three cycles of his five-days-a-month program, as you can see below and at 2:33 in my video. 

    One hundred men and women were randomized to consume his fasting-mimicking diet for five consecutive days per month or maintain their regular diet the whole time. As you can see in the graph below and at 2:47 in my video, after three months, the FMD group was down about six pounds compared to the control group, with significant drops in body fat and waist circumference, accompanied by a drop in blood pressure. 

    Those who were the worst off accrued the most dramatic benefits, as seen in the graph below and at 3:04 in my video. What’s even wilder is that three further months after completion, some of the benefits appeared to persist, suggesting the effects “may last for several months.” It’s unclear, though, if those randomized to the FMD group used it as an opportunity to make positive lifestyle changes that helped maintain some of the weight loss. 


    Dr. Longo created a company to market his meal plan commercially, but, to his credit, says “he does not receive a salary or a consulting fee from the company…and will donate 100% of his shares to charity.” The whole diet appears to be mostly dehydrated soup mixes, herbal teas like hibiscus and chamomile, kale chips, nut-based energy bars, an algae-based DHA supplement, and a multivitamin dusted with vegetable powder. Why spend 50 dollars a day on a few processed snacks when you could instead eat a few hundred calories a day of real vegetables? 
     
    How interesting was that? All-you-can-eat above-ground vegetables for five days would have the same low amount of protein, sugars, and calories with zero animal protein or animal fat. But we’ll probably never know if it works as well, better, or worse because it’s hard to imagine such a study ever getting done without the financial incentive. 

    To learn more about IGF-1, see my video Flashback Friday: Animal Protein Compared to Cigarette Smoking.
     
    In this series on fasting, I’ve covered several topics, including the basics of calories and weight loss, water-only fasting, and the types of alternate-day fasting, see them all in the related videos below. 
     
    I close out the series with videos on time-restricted eating: Time-Restricted Eating Put to the Test and The Benefits of Early Time-Restricted Eating. 
     
    If you want all of the videos in one place, I’ve done three webinars on fasting—Intermittent Fasting, Fasting for Disease Reversal, and Fasting and Cancer—and they’re all available for download now. 

    Michael Greger M.D. FACLM

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  • Is Our Life Expectancy Extended by Intermittent Fasting?  | NutritionFacts.org

    Is Our Life Expectancy Extended by Intermittent Fasting?  | NutritionFacts.org


    Alternate-day modified fasting is put to the test for lifespan extension. 

    Is it true that alternate-day calorie restriction prolongs life? Doctors have anecdotally attributed improvements in a variety of disease states to alternate-day fasting, including asthma; seasonal allergies; autoimmune diseases, such as rheumatoid arthritis and osteoarthritis; infectious diseases, such as toenail fungus, periodontal disease, and viral upper respiratory tract infections; neurological conditions, such as Tourette’s syndrome and Meniere’s disease; atrial fibrillation; and menopause-related hot flashes. The actual effect on chronic disease, however, remains unclear, as I discuss in my video Does Intermittent Fasting Increase Human Life Expectancy?. 
     
    Alternate-day fasting has been put to the test for asthma in overweight adults, and researchers found that asthma-related symptoms and control significantly improved, as did the patients’ quality of life, including objective measurements of lung function and inflammation. As you can see in the graphs below and at 0:56 in my video, there were significant improvements in peak airflow, mood, and energy. Their weight also improved—about a 19-pound drop in eight weeks—so it’s hard to tease out the effects specific to the fasting beyond the benefits we might expect from weight loss by any means. 

    For the most remarkable study on alternate-day fasting, you have to go back more than a half-century. Though the 2017 cholesterol findings were the most concerning data I could find on alternate-day fasting, the most enticing was published in Spain in 1956. The title of the study translates as “The Hunger Diet on Alternate Days in the Nutrition of the Aged.” Inspired by the data being published on life extension with caloric restriction on lab rats, researchers split 120 residents of a nursing home in Madrid into two groups. Sixty residents continued to eat their regular diet, and the other half were put on an alternate-day modified fast. On the odd days of the month, they ate a regular 2,300-calorie diet; on the even days, they were given only a pound of fresh fruits and a liter of milk, estimated to add up to about 900 calories. This continued for three years. So, what happened? 
     
    As you can see below and at 2:16 in my video, throughout the study, 13 participants died in the control group, compared to only 6 in the intermittent fasting group, but those numbers were too small to be statistically significant. 

    What was highly significant, though, was the number of days spent hospitalized: Residents in the control group spent a total of 219 days in the infirmary, whereas the alternate-day fasting group only chalked up 123 days, as you can see below and at 2:38 in my video. 


    This is held up as solid evidence that alternate-day fasting may improve one’s healthspan and potentially even one’s lifespan, but a few caveats must be considered. It’s not clear how the residents were allocated to their respective groups. If, instead of being randomized, healthier individuals were inadvertently placed in the intermittent fasting group, that could skew the results in their favor. As well, it appears the director of the study was also in charge of medical decisions at the nursing home. In that role, he could have unconsciously been biased toward hospitalizing more folks in the control group. Given the progress that has been made in regulating human experimentation, it’s hard to imagine such a trial being run today, so we may never know if such impressive findings can be replicated. 

    Well, that was interesting! I had never even heard of that study until I started digging into the topic.  

    Check out my fasting series and popular videos on the subject here.  

    For more on longevity, see related videos below.





    Michael Greger M.D. FACLM

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  • How Safe Is Alternate-Day Intermittent Fasting?  | NutritionFacts.org

    How Safe Is Alternate-Day Intermittent Fasting?  | NutritionFacts.org


    Eating every other day can raise your cholesterol. 
     
    Are there any downsides to fasting every other day? For example, might go all day without eating impair your ability to think clearly? Surprisingly, as I discuss in my video Is Alternate-Day Intermittent Fasting Safe?, the results appear to be “equivocal.” Some studies show no measurable effects and the ones that do fail to agree on which cognitive domains are affected. Might the cycles of fasting and feasting cause eating disorder–type behaviors, like bingeing? So far, no harmful psychological effects have been found. In fact, there may be some benefit. However, the studies that have put it to the test specifically excluded those with a documented history of eating disorders, for whom the effects may differ. 
     
    What about bone health? No change in bone mineral density was noted after six months of alternate-day fasting despite about 16 pounds of weight loss, which would typically result in a dip in bone mass. However, the researchers did not note any skeletal changes in the control group either, and they lost a similar amount of weight using continuous caloric restriction. They suggested this is because both groups tended to be “more physically active than the average obese American,” getting about 1,000 to 2,000 more steps a day. 
     
    Proponents of intermittent fasting suggest it can better protect lean body mass, but most of the intermittent trials have employed less accurate methods of body composition analysis, whereas the majority of continuous caloric restriction trials used “vastly more accurate techniques.” So, to date, it is not clear if there’s a difference in lean mass preservation. 
     
    Improvements in blood pressure and triglycerides have been noted on intermittent fasting regimens, though this is presumed to be due to the reduction in body fat since the effect appears to be “dependent on the amount of weight lost.” Alternate-day fasting can improve artery function, too, as you can see in the graph below and at 1:55 in my video, though it does depend on what you’re eating on the non-fasting day. For study participants randomized to an alternate-day diet high in saturated fat, their artery function worsened despite a ten-pound weight loss, whereas it improved, as expected, in the lower-fat group. The decline in artery function was presumed to be because of the pro-inflammatory nature of saturated fat. 

    A concern has been raised about the effects of alternate-day fasting on cholesterol. After 24 hours without food, LDL cholesterol may temporarily bump up, but this is presumably because so much fat is being released into the system by the fast. As you can see in the graph below and at 2:33 in my video, an immediate negative effect on carbohydrate tolerance may stem from the same phenomenon—the repeated elevations of free fat floating around in the bloodstream. After a few weeks, though, LDL levels start to drop as the weight comes off. However, results from the largest and longest trial of alternate-day fasting have given me pause. 


    A hundred obese men and women were randomized into one of three groups: alternate-day modified fasting (25 percent of their baseline calories on fasting days and 125 percent calories on eating days), continuous, daily caloric restriction (75 percent of baseline), or a control group instructed to maintain their regular diet. So, for those going into the trial eating 2,000 calories a day, they would continue to eat 2,000 calories a day in the control group. The calorie-restriction group would get 1,500 calories every day, and the intermittent-restriction group would alternate between 500 calories a day and 2,500 calories the next. 
     
    As you can see in the graph below and at 3:32 in my video, with the same overall, average, prescribed calorie cutting in the two weight-loss groups, they both lost about the same amount of weight, but, surprisingly, the cholesterol effects were different. In the continuous calorie-restriction group, the LDL levels dropped as expected compared to the control group as the pounds came off. 

    But, in the alternate-day modified fasting group, they didn’t, as you can see below, and at 3:55 in my video. At the end of the year, the LDL cholesterol in the intermittent fasting group ended up being 10 percent higher than in the constant calorie-restriction group—despite the same loss of body fat. Given that LDL cholesterol is a prime causal risk factor for heart disease, our number one killer—or is even the prime risk factor—this strikes a significant blow against alternate-day fasting. If you want to try it anyway, I would advise you to have your cholesterol monitored to make sure it comes down with your weight. 


    If you’re diabetic, you must talk with your physician about medication adjustment for any changes in diet, including fasting of any duration. Even with proactive medication reduction, advice to immediately break the fast should sugars drop too low, and weekly medical supervision, people with type 2 diabetes who fasted for even just two days a week were twice as likely to suffer from hypoglycemic episodes compared to an unfasted control group. We still don’t know the best way to tweak blood sugar medications to prevent blood sugar from dropping too low on fasting days. 
     
    Even fasting for just one day can significantly slow the clearance of some drugs (like the blood-thinning drug Coumadin) or increase the clearance of others (like caffeine). Fasting for 36 hours can cut your caffeine buzz by 20 percent. So, consultation with your medical professional before fasting is an especially good idea for anyone on any kind of medication. 

    If you missed it, check out Alternate-Day Intermittent Fasting Put to the Test. 
     
    So, with ambiguous cognitive, lean mass, and bone effects, plus these cholesterol findings, I wouldn’t suggest alternate-day fasting for weight loss, but dropping pounds isn’t the only thing this way of eating is purported to do. Check out Does Intermittent Fasting Increase Human Life Expectancy?. 
     
    For other types of intermittent fasting, total fasting, and more on fasting, check out the related videos below. 





    Michael Greger M.D. FACLM

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  • Putting Alternate-Day Intermittent Fasting to the Test  | NutritionFacts.org

    Putting Alternate-Day Intermittent Fasting to the Test  | NutritionFacts.org


    Does eating every other day prevent the metabolic slowing that accompanies weight loss, or does it improve compliance over constant, day-to-day caloric restriction? 

    Rather than cutting calories day in and day out, what if you instead ate as much as you wanted every other day or for only a few hours a day? Or, what if you fasted two days a week or five days a month? These are all examples of intermittent fasting regimens, as you can see below and at 0:10 in my video Alternate-Day Intermittent Fasting Put to the Test, and that may even be how we were built. Three meals a day may be a relatively novel behavior for our species. For millennia, “our ancestors could not eat three meals every day. They consumed meals much less frequently, and often consumed one large meal per day or went for several days without food.” 

    Intermittent fasting is often presented as a means of stressing your body—in a good way. There is a concept in biology called hormesis, which can be thought of as the “that which doesn’t kill you makes you stronger” principle. Exercise is the classic example: You put stress on your heart and muscles, and as long as there is sufficient recovery time, you are all the healthier for it. Is that the case with intermittent fasting? Mark Twain thought so: “A little starvation can really do more for the average sick man than can the best medicines and the best doctors. I do not mean a restricted diet, I mean total abstention from food for one or two days.” 
     
    But, Twain also said, “Many a small thing has been made large by the right kind of advertising.” Is the craze over intermittent fasting just hype? Many diet fads have their roots “in legitimate science,” but over time, facts can get distorted, benefits exaggerated, and risks downplayed. In other words, “science takes a back seat to marketing.” At the same time, you don’t want to lose out on any potential benefit by dismissing something out of hand based on the absurdist claims of overzealous promoters. You don’t want to throw the baby out with the baby fat. 
     
    Religious fasting is the most studied form of intermittent fasting, specifically Ramadan, a month-long period in which “Muslims abstain from food and drink from sunrise until sunset.” The effects are complicated by a change in sleeping patterns and also thirst. The same dehydration issue arises with Yom Kippur when observant Jews stop eating and drinking for about 25 hours. The most studied form of intermittent fasting that deals only with food restriction is alternate-day fasting, which involves eating every other day, alternating with days consuming little or no calories. 
     
    At rest, we burn about a 50:50 mix of carbohydrates and fat, but we usually run out of glycogen—our carbohydrate stores—within 12 to 36 hours of stopping eating. At that point, our body has to shift to rely more on our fat stores. This metabolic switch may help explain why the greatest rate of breakdown and burning of fat over a three-day fast happens between hours 18 and 24 of the 72 hours. The hope is to reap some of the benefits of taking a break from eating without the risks of prolonged fasting. 
     
    One of the potential benefits of alternate-day fasting over chronic calorie restriction is that you get regular breaks from feeling constant hunger. But might people become so famished on their fasting day that they turn the next into a feasting day? After your fasting day, if you ate more than twice as much as you normally would, that presumably would defeat the whole point of alternate-day fasting. Mice fed every other day don’t lose weight. They just eat roughly twice as much food in one day as non-fasted mice would regularly eat in two days. That is not, however, what happens in people. 
     
    Study participants were randomized to fast for a day and a half—from 8:00 p.m. to 8:00 a.m. the second morning after beginning. Fasting for 36 hours only led to people eating an average of 20 percent more the day after they broke the fast, compared to a control group who didn’t fast at all. That would leave the fasters with a large calorie deficit, equivalent to a daily caloric restriction of nearly a thousand calories a day. This particular study involved lean men and women, but similar results have been found amongst overweight or obese subjects. Researchers typically found only about a 10 to 25 percent compensatory increase in calorie intake over baseline on non-fasting days, and this seems to be the case whether the fasting day was a true zero-calorie fast or a modified fast day of a few hundred calories, which may lead to better compliance. 
     
    Some studies have found that participants appeared to eat no more, or even eat less, on days after a day-long mini-fast. Even within studies, great variability is reported. In a 24-hour fasting study where individuals ate an early dinner and then had a late dinner the next day after skipping breakfast and lunch, the degree of compensation at the second dinner ranged from 7 percent to 110 percent, as you can see in the graph below and at 4:40 in my video. This means that some of the participants got so hungry by the time supper rolled around that they ate more than 24 hours’ worth of calories in a single meal. The researchers suggested that perhaps people first try “test fasts” to see how much their hunger and subsequent intake ramp up before considering an intermittent fasting regimen. Hunger levels can change over time, though, dissipating as your body habituates to the new normal. 


    In an eight-week study in which obese subjects were restricted to about 500 calories every other day, after approximately two weeks, they reportedly started feeling very little hunger on their slashed calorie days. This no doubt helped them lose about a dozen pounds on average over the duration of the study, but there was no control group with whom to compare. A similar study that did have a control group found a similar amount of weight loss—about ten pounds—over 12 weeks in a group of “normal weight” individuals, which means overweight on average. For these modified regimens where people are prescribed 500 calories on their “fasting” days, researchers found that, from a weight-loss perspective, it did not appear to matter whether those calories are divided up throughout the day or eaten in a single meal. 
     
    Instead of prescribing a set number of calories on “fasting” days, which many people find difficult to calculate outside of a study setting, a pair of Iranian researchers came upon a brilliant idea of unlimited above-ground vegetables. Starchy root vegetables are relatively calorie-dense compared to other vegetables. Veggies that grow above the ground include stem vegetables (like celery and rhubarb), flowering vegetables (like cauliflower), leafy vegetables (like, well, leafy vegetables), and all of the fruits we tend to think of as vegetables (like tomatoes, peppers, okra, eggplant, string beans, summer squash, and zucchini). So, instead of prescribing a certain number of calories for “fasting” days, researchers had subjects alternate between their regular diet and helping themselves to an all-you-can-eat, above-ground vegetable feast (along with naturally non-caloric beverages, like green tea or black coffee) every other day. After eight weeks, the subjects lost an average of 13 pounds and two inches off their waist, as you can see below and at 6:59 in my video. 


    The same variability discovered for calorie compensation has also been found for weight loss, as seen in the graph below and at 7:10 in my video. In a 12-month trial in which subjects were instructed to eat only one-quarter of their caloric needs every other day, weight changes varied from a loss of about 37 pounds to a gain of about 8 pounds. The biggest factor differentiating the low-weight-loss group from the high-weight-loss group appeared to be not how much they feasted on their regular diet days, but how much they were able to comply with the calorie restriction on their fast days. 

     
    Overall, ten out of ten alternate-day fasting studies showed significant reductions in body fat. Small short-term studies show about a 4 to 8 percent drop in body weight after 3 to 12 weeks. How does that compare with continuous calorie restriction? Researchers compared zero-calorie, alternate-day fasting head-to-head to a daily 400-calorie restriction for eight weeks. Both groups lost the same amount of weight, about 17 pounds, and, in the follow-up check-in six months later after the trial had ended, both groups had maintained a similar degree of weight loss; both were still down about a dozen pounds, as you can see below and at 8:10 in my video. 


    The hope that intermittent fasting would somehow avoid the metabolic adaptations that slow weight loss or improve compliance doesn’t seem to have materialized. The same compensatory reactions in terms of increased appetite and a slower metabolism plague both continuous and intermittent caloric restriction. The longest trial of alternate-day fasting found that “alternate-day fasting may be less sustainable” than more traditional approaches. By the end of the year, the drop-out rate of the alternate-day fasting group was 38 percent, compared to 29 percent in the continuous calorie-restriction group.  

    Although alternate-day fasting regimens haven’t been shown to produce superior weight loss to date, for individuals who may prefer this pattern of calorie restriction, are there any downsides? Find out in my video Is Alternate-Day Intermittent Fasting Safe?. 
     
    I packed a lot into this one. Bottom line: Fasting doesn’t appear to provide an edge over traditional calorie cutting, but if you prefer it, why not give fasting a try? Before you do, first check out Is Alternate-Day Intermittent Fasting Safe?.  

    What about total fasting? For that and even more, check out the related videos below.

    I have a whole chapter on intermittent fasting in my book How Not to Diet—order now! (All proceeds I receive from my books are donated to charity.) 





    Michael Greger M.D. FACLM

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  • The Safety of Fasting to Lose Weight  | NutritionFacts.org

    The Safety of Fasting to Lose Weight  | NutritionFacts.org

    Why should fasts lasting longer than 24 hours and particularly for three or more days only be done under the supervision of a health professional and preferably in a live-in clinic? 
     
    Fasting for a week or two can actually interfere with the loss of body fat, as shown at the start of my video Is Fasting for Weight Loss Safe?. But, eventually, after the third week of fasting, fat loss starts to overtake the loss of lean body mass in obese individuals, as seen in the graph below and at 0:14 in my video. Is it safe to go that long without food? 

    Proponents speak of fasting as a cleansing process, but some of what is being purged from our bodies are essential vitamins and minerals. People who are heavy enough can fast up to 382 days without calories, but no one can go even a fraction of that long without vitamins. Scurvy, for example, can be diagnosed within as few as four weeks without any vitamin C. Beriberi, deficiency of thiamine (vitamin B1), may start even earlier in fasting patients. And, once it manifests, it can result in brain damage within days, which can eventually become irreversible.  
     
    Even though fasting patients report problems such as nausea and indigestion after taking supplements, all of the months-long fasting cases I’ve discussed previously were given daily multivitamins and mineral supplementation as necessary. Without supplementation, hunger strikers and those undergoing prolonged fasts for therapeutic or religious purposes (like the Baptist pastor hoping “to enhance his spiritual powers for exorcism”) have ended up paralyzed, become comatose, or worse. 
     
    Nutrient deficiencies aren’t the only risk. After reading about all of the successful reports of massive weight loss from prolonged fasting in the medical literature, one doctor decided to give it a try with his patients. Of the first dozen he tried it on, two died. In retrospect, the two patients who died had started out with heart failure and had been on diuretics. Fasting itself produces pronounced diuresis, meaning loss of water and electrolytes through the urine, so it was the combination of fasting on top of the water pills that likely depleted their potassium and triggered their fatal heart rhythms. The doctor went out of his way to point out that both of the people who died started out “in severe heart failure, complicated by gross obesity; but both had improved greatly whilst undergoing starvation therapy.” That seems like a small consolation since they were both dead within a matter of weeks. 
     
    Not all therapeutic fasting fatalities were complicated by concurrent medication use, though. One researcher writes: “At first he did very well and experienced the usual euphoria…His pulse, blood pressure, and electrolytes remained satisfactory, but in the middle of the third week of treatment, he suddenly collapsed and died. This line of treatment is certainly tempting because it does produce weight loss and the patient feels so much better, but the report of case-fatalities”—the whole part about killing people—“must make it a very suspect line of management.” 
     
    Contrary to the popular notion that the heart muscle is specially spared during fasting, the heart appears to experience similar muscle wasting. This was “described in the victims of the Warsaw ghetto” during World War II in a remarkable series of detailed studies carried out by the ghetto physicians before they themselves succumbed. In a case entitled “Gross Fragmentation of Cardiac Fiber After Therapeutic Starvation for Obesity,” a 20-year-old woman successfully “achieved her ideal weight” after losing 128 pounds by fasting for 30 weeks. “After a breakfast of one egg,” she had a heart attack and died. On autopsy, as you can see below and at 3:44 in my video, the muscle fibers in her heart showed evidence of widespread disintegration. The pathologists suggested that fasting regimens “should no longer be recommended as a safe means of weight reduction.” 
    Breaking the fast appears to be the most dangerous part. After World War II, as many as one out of five starved Japanese prisoners of war tragically died following liberation. Now known as “refeeding syndrome,” multiorgan system failure can result from resuming a regular diet too quickly. This is because there are critical nutrients such as thiamine and phosphorus that are used to metabolize food. Therefore, in the critical refeeding window, if too much food is taken before these nutrients can be replenished, demand may exceed supply. Whatever residual stores you still carry can be driven down even further, with potentially fatal consequences. This is why rescue workers are taught to always give thiamine before food to victims who have been trapped or otherwise unable to eat. Thiamine is responsible for the yellow color of “banana bags,” a term you might have heard used in medical dramas to describe an IV fluid concoction often given to malnourished alcoholics to prevent a similar reaction. (You can see a photo of them below and at 4:53 in my video.) Anyone “with negligible food intake for more than five days” may be at risk of developing refeeding problems. 
    Medically-supervised fasting has gotten much safer now that there are proper refeeding protocols. We now know what warning signs to look for and who shouldn’t be fasting in the first place, such as those who have advanced liver or kidney failure, porphyria, uncontrolled hyperthyroidism, and pregnant and breastfeeding women. The most comprehensive safety analysis of medically supervised, water-only fasting was recently published by the TrueNorth Health Center in California. Out of 768 visits to its facility for fasts up to 41 days, were there any adverse events? There were 5,961 of them! Most of these were mild, known reactions to fasting, such as fatigue, nausea, insomnia, headache, dizziness, upset stomach, and back pain. Only two serious events were reported, and no fatalities. You can see the chart below and at 5:58 in my video. 
    “Fasting periods lasting longer than 24 hr, and particularly those lasting 3 or more days, should be done under the supervision of a physician and preferably in a [live-in] clinic.” In other words, don’t try this at home! This is not just legalistic mumbo-jumbo. For example, normally, your kidneys dive into sodium conservation mode during fasting, but should that response break down, you could rapidly develop an electrolyte abnormality that may only manifest with non-specific symptoms, like fatigue or dizziness, which could easily be dismissed until it’s too late. 
     
    The risks of any therapy must be premised on the severity of the disease. The consequences of obesity are considered so serious that effective therapies could have “considerable acceptable toxicity.” For example, many consider major surgery for obesity to be a justifiable risk, but the keyword is effective. 
     
    Therapeutic fasting for obesity has largely been abandoned by the medical community not only because of its uncertain safety profile but its questionable short- and long-term efficacy. Remember, for a fast that only lasts a week or two, you might be able to lose as much body fat or even more on a low-calorie diet than a no-calorie diet. 
     
    Fasting for a week or two can actually interfere with the loss of body fat. For more background on this, see Is Fasting Beneficial for Weight Loss? and Benefits of Fasting for Weight Loss Put to the Test.
     
    If you’re wondering what the best way to lose weight is, I wrote a whole book about it! Check out How Not to Diet. 
     
    Interested in learning more about fasting? See related videos below. 

    Michael Greger M.D. FACLM

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  • Does Fasting Benefit Weight Loss?  | NutritionFacts.org

    Does Fasting Benefit Weight Loss?  | NutritionFacts.org

    Like the keto diet, fasting for one or two weeks can actually slow the loss of body fat rather than accelerate it.

    Fasting obviously causes consistent, dramatic weight loss, as shown in the graph below and at 0:09 in my video Is Fasting Beneficial for Weight Loss?, but how do fasted individuals do long-term? Some research groups reported “extremely disappointing long-term effects,” as you can see in the graph below and at 0:19 in my video. 

    Average subjects started at about 270 pounds and, in the six months before the fast, continued to gain weight as obese persons tend to do. After 24 days of “inpatient starvation,” they experienced a dramatic 27-pound weight loss. Then, what do you think happened?

    They gained it all back and more, though one could argue if they had not fasted, they might have weighed even more at that point, as seen in the graph below and at 0:45 in my video. 
    In another study with follow-ups ranging up to 50 months, only 4 out of 25 “superobese” patients achieved even partial sustained success. Based on these kinds of data, some investigators “concluded that complete starvation is of no value in the long-term treatment of obese patients.” 
     
    Other research teams reported better outcomes. One series with about 100 individuals found that 60 percent retained at least some weight loss at follow-up or even continued losing. The follow-up periods varied from 1 to 32 months with no breakdown as to who fasted and for how long, though, making the data hard to interpret. In another study, 62 patients were down an average of 16 pounds after fasting for 10 days. After one year, 40 percent of the group had retained at least 7 pounds of that weight loss. 
     
    As you can see below and at 1:37 in my video, when you put together six such studies, hundreds of obese subjects fasted for an average of 44 days and lost an average of 52 pounds. And, around one or two years later, 40 percent retained at least some of that weight loss. So, most gained back all of the weight they had lost, but 40 percent is extraordinary for a weight-loss study. 

    Following a hundred obese individuals getting treated at a weight-loss clinic with a standard low-calorie diet, researchers found that only one out of a hundred lost more than 40 pounds and only about one in ten lost even 20 pounds, with overall successful weight maintenance at only two patients over two years, as seen below and at 2:08 in my video. That’s why having a control group is so important. What may look like a general failure may actually be a relative success compared to more traditional weight-loss techniques. 

    Researchers new to the field may find it “clearly disappointing” that the “overall results of follow-up for 12 months or more” found that “two-thirds of the patients were ‘failures’ and more than one-third actually regained all the weight lost.” But, 12 percent were labeled successes, maintaining 59 pounds of weight loss two years later. As you can see in the graph below and at 2:42 in my video, the subjects lost massive amounts of excess weight and kept it off. 

    In a direct comparison of different weight-loss approaches at the same clinic, five years after initiating a conventional low-calorie approach, only about one in five was down 20 pounds compared to nearly half in the group who instead had undergone a few weeks of fasting years previously. By year seven, as you can see in the graph below and at 3:03 in my video, most of those instructed on daily caloric restriction were back up to their original weight or had even exceeded it, but that was only true for about one in ten in the fasted group. In an influential paper in the New England Journal of Medicine on seven myths about obesity, fallacy number three was identified as: “Large, rapid weight loss is associated with poorer long-term weight-loss outcomes, as compared with slow, gradual weight loss.” In reality, the opposite is true. The hare may end up skinnier than the turtle.  

    As shown in the graph below and at 3:39 in my video, researchers set up a study comparing the sustainability of weight loss at three different speeds: six days of fasting, three weeks on a very-low-calorie diet of 600 calories a day, or six weeks on a low-calorie diet of 1,200 calories a day. 

    The question is: What happened a year later? At one year, the fasting group was the only one that sustained a significant loss of weight, as you can see below and at 3:55 in my video. 

    What happened nine years later? “Therapeutic Fasting in Morbid Obesity” is the largest, longest follow-up study I could find. At least some of the fast-induced weight losses were maintained a year later by the great majority. After one year, 90 percent remained lighter than they had started, but after two years, three years, four years, and seven years, fewer and fewer patients maintained their weight loss. By nine years later, that number dropped to fewer than one in ten. By then, almost everyone had regained the weight they had initially fasted away, as you can see in the graph below and at 4:17 in my video. “Many patients thought that the temporary loss was worth the effort,” though. As a group, they had lost an average of about 60 pounds. They described improved health and quality of life and claimed that “reemployment was facilitated and earnings increased” during that period of time. But the fasting didn’t appear to result in any permanent change in eating habits for the vast majority. 
    The small minority for whom fasting led to sustainable weight loss “all admit to a radical change in previous eating habits”; indeed, fasting only works long-term if it can act as a jumpstart to a healthier diet. In a retrospective long-term comparison of weight reduction after an inpatient stay at a naturopathic center, those who fasted lost more weight at the time, but they were back to the same weight at around seven years, as you can see in the graph below and at 5:14 in my video. 

    It’s no surprise since most reported returning to the same diet they had been on before. However, those who were placed instead on a healthier, more whole food, plant-based diet were more likely to make persistent changes in their eating and, seven years later, were lighter than when they started, as you can see in the graph below and at 5:36 in my video. 

    Why can’t you have it both ways, though? Use fasting to kickstart a big drop, then start a healthier diet. The problem is that the big drop is largely illusory, as you can see in the graph below and at 5:48 in my video. 

    Fasting for a week or two can cause more weight loss than caloric restriction, but, paradoxically, it may actually lead to less loss of body fat. How can eating fewer calories lead to less fat loss? Because during fasting, your body starts cannibalizing itself and burning more of your own protein for fuel. Emperor penguins, elephant seals, and hibernating bears can survive by just burning fat without dipping into their muscles, but our voracious big brains appear to need at least a trickle of blood sugar. If we aren’t eating any carbohydrates, our body is forced to start turning our protein into sugar to burn. Even getting just a few grams of carbs—from adding honey to water when fasting, for instance—can cut protein loss up to 50 percent.  

    What about adding exercise to prevent the loss of lean tissues during a fast? That may make it worse! At rest, most of your heart and muscle energy needs can be met with fat, but if you start exercising, some of the blood sugar meant for your brain starts getting snatched up and your body may have to break down even more protein. 
     
    As you can see in the graph below and at 7:00 in my video, less than half of the weight loss during the first few weeks of fasting ends up coming from your fat stores. So, even if you double your daily weight loss on a fast, you may be actually losing less body fat. 

    In an NIH-funded study, obese individuals were placed on an 800-calorie-a-day diet for two weeks and steadily lost about a pound of body fat a day. They were then switched to about two weeks of zero calories and started losing more protein and water. On average, though, they only lost a few ounces of fat daily. When they were subsequently switched back to the initial 800-calories-a-day diet for a week, they rapidly replaced the protein and water, so the scale registered their weight as going up, but their body fat loss accelerated back to the approximate pound a day. The scale made it look as though they were doing better when they were completely fasting, but the reality is they were doing worse. So, during the five-week experiment, they would have lost even more body fat had they stuck with their calorie-restricted diet rather than completely stopping eating in the middle. They would have lost more body fat by eating more calories. Fasting for a week or two can interfere with the loss of body fat, rather than accelerate it. You can see a series of graphs depicting this from 7:13 in my video, including the one below. 

    This is the follow-up to Benefits of Fasting for Weight Loss Put to the Test. It seems fasting may only work long-term if it can act as a jumpstart to a healthier diet, and just fasting for a week or two can be counterproductive, like the keto diet. Is it even safe to fast longer than that? Find out in Is Fasting for Weight Loss Safe?. 
     
    For more on the keto story and more on fasting for weight loss, see related videos below. 
     
    I’ve done my third live webinar on fasting, Fasting and Cancer. Those videos are also on NutritionFacts.org. 

    Michael Greger M.D. FACLM

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  • Putting the Benefits of Fasting for Weight Loss to the Test  | NutritionFacts.org

    Putting the Benefits of Fasting for Weight Loss to the Test  | NutritionFacts.org

    For more than a century, fasting has been used as a weight-loss treatment.

    I’ve talked about the benefits of caloric restriction. Well, the greatest caloric restriction is getting no calories at all. Fasting has been branded “the next big weight loss fad,” but it has a long history throughout various spiritual traditions, practiced by Moses, Jesus, Muhammed, and Buddha. In 1732, a noted physician wrote, “He that eats till he is sick must fast till he is well.” About one in seven American adults today report taking that advice, “using fasting as a means to control body weight,” as I discuss in my video Benefits of Fasting for Weight Loss Put to the Test. 
     
    Case reports of the treatment of obesity through fasting date back more than a century in the medical literature. In 1915, two Harvard doctors indelicately described “two extraordinarily fat women,” one of whom “was a veritable pork barrel.” Their success led them to conclude that “successive moderate periods of starvation constitute a perfectly safe, harmless, and effective method for reducing the weight of those suffering from obesity.” 
     
    The longest-recorded fast, published in 1973, made it into the Guinness Book of World Records. To reach his ideal body weight, a 27-year-old man fasted for 382 days straight, losing 276 pounds, and managed to keep nearly all of it off. He was given vitamin and mineral supplements so he wouldn’t die, but no calories for more than a year. In the researchers’ acknowledgments, they thanked him “for his cheerful co-operation and steadfast application to the task of achieving a normal physique.” 
     
    In a U.S. Air Force study, more than 20 individuals at least 100 pounds overweight and most “unable to lose weight on previous diets” were fasted for as long as 84 days. Nine dropped out of the study, but the 16 who remained “were unequivocally successful” at losing 40 to 100 pounds. In the first four days, the subjects were noted as losing as much as four pounds a day, which “probably represents mostly fluid,” mostly water weight as the body starts to adapt. But, after a few weeks, they were steadily losing about a pound a day of mostly straight fat. The investigator described the starvation program as “a dramatic and exciting treatment for obesity.” 
     
    Of course, the single most successful diet for weight loss—namely no diet at all—is also the single least sustainable. What other diet can cure morbid obesity in a matter of months but practically be guaranteed to kill you within a year if you stick with it? The reason diets don’t work, almost by definition, is that people go on them, then they go off of them. Permanent weight loss is only achieved through permanent lifestyle change. So, what’s the point of fasting if you’re just going to go back to your regular diet and gain right back all of that lost weight? 
     
    Fasting proponents cite the psychological benefit of realigning people’s perceptions and motivation. Some individuals have resigned themselves to the belief that weight loss for them is somehow impossible. They may think “that they are ‘made differently’ from those of normal weight” in some way, and no matter what they do, the pounds don’t come off. But the rapid, unequivocal weight loss during fasting demonstrates to them that with a large enough change in eating habits, it’s not just possible, but inevitable. This morale boost may then embolden them to make better food choices once they resume eating. 
     
    The break from food may allow some an opportunity “to pause and reflect” on the role food is playing in their lives—not only the power it has over them but the power they have over it. In a fasting study entitled “Correction and Control of Intractable Obesity,” a patient’s personality was described as changing “from one of desperation, with abandonment of hope, to that of an eager extravert full of plans for a promising future.” She realized that her weight was within her own power to control. The researchers concluded: “This highly intellectual social worker has been returned to a full degree of exceptional usefulness.” 
     
    After a fast, newfound commitment to more healthful eating may be facilitated by a reduction in overall appetite reported post-fast, compared to pre-fast, at least temporarily. Even during a fast, hunger may start to dissipate within the first 36 hours. So, challenging people’s delusions about their exceptionality to the laws of physics—thinking they are “made differently”—with “short periods of total fasting may seem barbaric. In reality, this method of weight reduction is remarkably well tolerated by obese patients.” That seems to be a recurring theme in these published series of cases. In the influential paper “Treatment of Obesity by Total Fasting for up to 249 Days,” the researchers remarked that the “most surprising aspect of this study was the ease with which the prolonged fast was tolerated.” All of their patients “spontaneously commented on their increased sense of well-being, and in some, this amounted to frank euphoria.” They continued that, although “treatment by total fasting must only be prescribed under close medical supervision,” they “are convinced that it is the treatment of choice, certainly in cases of gross obesity.” 
     
    Fasting for a day can make people irritable and feel moody and distracted, but after a few days of fasting, many report feeling clear, elated, and alert—even euphoric. This may be in part due to the significant rise in endorphins that accompanies fasting, as you can see in the graph below and at 5:48 in my video. Mood enhancement during fasting is thought to perhaps represent an adaptive survival mechanism to motivate the food search. This positive outlook towards the future may then facilitate the behavioral change necessary to lock in some of the weight-loss benefits. 

    Is that what happens, though? Is fasting actually effective over the long term? There are articles with titles like “Death During Therapeutic Starvation for Obesity.” Is fasting even safe? We’ll find out next. 
     
    This is the sixth in a 14-part series on fasting for weight loss. In case you missed any of the others, see the related videos below. 

    My book How Not to Diet is all about weight loss. You can learn more about it and order it here. 

    Michael Greger M.D. FACLM

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  • Restricting Calories for Longevity?  | NutritionFacts.org

    Restricting Calories for Longevity?  | NutritionFacts.org

    Though a bane for dieters, a slower metabolism may actually be a good thing.

    We’ve known for more than a century that calorie restriction can increase the lifespan of animals, and metabolic slowdown may be the mechanism. That could be why the tortoise lives ten times longer than the hare. Rabbits can live for 10 to 20 years, whereas “Harriet,” a tortoise “allegedly collected from the Galapagos Islands by Charles Darwin, was estimated to be about 176 years old when she died in 2006.” Slow and steady may win the race. 
     
    As I discuss in my video The Benefits of Calorie Restriction for Longevity, one of the ways our body lowers our resting metabolic rate is by creating cleaner-burning, more efficient mitochondria, the power plants that fuel our cells. It’s like our body passes its own fuel-efficiency standards. These new mitochondria create the same energy with less oxygen and produce less free radical “exhaust.” After all, when our body is afraid famine is afoot, it tries to conserve as much energy as it can. 
     
    Indeed, the largest caloric restriction trial to date found metabolic slowing and a reduction in free radical-induced oxidative stress, both of which may slow the rate of aging. The flame that burns twice as bright burns half as long. But, whether this results in greater human longevity is an unanswered question. Caloric restriction is often said “to extend lifespan in every species studied,” but that isn’t even true of all strains within a single species. Two authors of one article, for instance, don’t even share the same view: One doesn’t think calorie restriction will improve human longevity at all, while the other suggests that a 20 percent calorie restriction starting at age 25 and sustained for 52 years could add five years onto your life. Either way, the reduced oxidative stress would be expected to improve our healthspan. 
     
    Members of the Calorie Restriction Society, self-styled CRONies (for Calorie-Restricted Optimal Nutrition), appear to be in excellent health, but they’re a rather unique, self-selected group of individuals. You don’t really know until you put it to the test. Enter the CALERIE study, the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy, the first clinical trial to test the effects of caloric restriction. 
     
    Hundreds of non-obese men and women were randomized to two years of 25 percent calorie restriction. They only ended up achieving half that, yet they still lost about 18 pounds and three inches off their waists, wiping out more than half of their visceral abdominal fat, as you can see in the graph below and at 2:47 in my video. 

    That translated into significant improvements in cholesterol levels, triglycerides, insulin sensitivity, and blood pressure, which you can see in the graph below and at 2:52 in my video. Eighty percent of those who were overweight when they started were normal-weight by the end of the trial, “compared with a 27% increase in those who became overweight in the control group.” 

    In the famous Minnesota Starvation Study that used conscientious objectors as guinea pigs during World War II, the study subjects suffered both physically and psychologically, experiencing depression, irritability, and loss of libido, among other symptoms. The participants started out lean, though, and had their calorie intake cut in half. The CALERIE study ended up being four times less restrictive, only about 12 percent below baseline calorie intake, and enrolled normal-weight individuals, which in the United States these days means overweight on average. As such, the CALERIE trial subjects experienced nothing but positive quality-of-life benefits, with significant improvements in mood, general health, sex drive, and sleep. They only ended up eating about 300 fewer calories a day than they had eaten at baseline. So, they got all of these benefits—the physiological benefits and the psychological benefits—just from cutting about a small bag of chips’ worth of calories from their daily diets. 
     
    What happened at the end of the trial, though? As researchers saw in the Minnesota Starvation Study and in calorie deprivation experiments done on Army Rangers, as soon as the subjects were released from restriction, they tended to rapidly regain the weight and sometimes even more, as you can see below and at 4:18 in my video. 

    The leaner they started out, the more their bodies seemed to drive them to overeat to pack back on the extra body fat, as seen in the graph below and at 4:27 in my video. In contrast, after the completion of the CALERIE study, even though their metabolism was slowed, the participants retained about 50 percent of the weight loss two years later. They must have acquired new eating attitudes and behaviors that allowed them to keep their weight down. After extended calorie restriction, for example, cravings for sugary, fatty, and junky foods may actually go down. 
    This is part of my series on calorie restriction, intermittent fasting, and time-restricted eating. See related videos below.

    Michael Greger M.D. FACLM

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  • Sugar and Gaining Weight  | NutritionFacts.org

    Sugar and Gaining Weight  | NutritionFacts.org

    The sugar industry responds to evidence implicating sweeteners in the obesity epidemic. 
     
    In terms of excess body fat, the “well-documented obesity epidemic may merely be the tip of the overfat iceberg.” It’s been estimated that 91 percent of adults—nine out of ten of us—and 69 percent of children in the United States are overfat, a condition defined as having “excess body fat sufficient to impair health.” This can occur even in individuals who are “normal-weight and non-obese, often due to excess abdominal fat.” The way to tell if you’re overfat is if your waist circumference is more than half your height. What’s causing this epidemic? As I discuss in my video Does Sugar Lead to Weight Gain?, one primary cause may be all the added sugars we’re eating. 
     
    A century ago, sugar was heralded as one of the cheapest forms of calories in the diet. Just ten cents’ worth of sugar could furnish thousands of calories. Dr. Fredrick Stare, “Harvard’s sugar-pushing nutritionist,” bristled at the term “empty calories,” writing that the calories in sugar were “not empty but full of energy”—in other words, full of calories, which we are now getting too much of. The excess bodyweight of the U.S. population corresponds to about a daily 350- to 500-calorie excess on average. So, “to revert the obesity epidemic,” that’s how many calories we have to reduce, but which calories should we cut? As you can see below and at 1:33 in my video, the majority of Americans who fail to meet the Dietary Guidelines’ sugar limit get about that many calories in added sugars every day: Twenty-five teaspoons’ worth of added sugars is about 400 calories. 

    There are die-hard sugar defenders. James Rippe, for example, was reportedly paid $40,000 a month by the high fructose corn syrup industry—and that was on top of the $10 million it paid for his research. Even Dr. Rippe considers it “undisputable that sugars…contribute to obesity. It is also undisputable that sugar reduction…should be part of any weight loss program.” And, of all sources of calories to limit, since sugar is just empty calories and contains no essential nutrients, “reducing sugar consumption is obviously the place to start.” And, again, this is what the researchers funded by the likes of Dr. Pepper and Coca-Cola are saying. The primary author of “Dietary Sugar and Body Weight: Have We Reached a Crisis in the Epidemic of Obesity and Diabetes?…,” Richard Kahn, is infamous for his defense of the American Beverage Association—the soda industry—and he was the chief science officer at the American Diabetes Association when it signed a million-dollar sponsorship deal with the world’s largest candy company. “Maybe the American Diabetes Association should rename itself the American Junk Food Association,” said the director of a consumer advocacy group. What do you expect from an organization that was started with drug industry funding? 
     
    The bottom line is that “randomised controlled trials show that increasing sugars intake increases energy [calorie] intake” and “increasing sugar intake leads to body weight gain in adults, and…sugar reduction leads to body weight loss in children.” For example, when researchers randomized individuals to either increase or decrease their intake of table sugar, the added sugar group gained about three and a half pounds over ten weeks, whereas the reduced sugar group lost about two and a half pounds. A systematic review and meta-analysis of all such ad libitum diet studies—real-life studies where sugar levels were changed but people could otherwise eat whatever they wanted—found that reduced intake of dietary sugars resulted in a decrease in body weight, whereas “increased sugars intake was associated with a comparable weight increase.” The researchers found that, “considering the rapid weight gain that occurs after an increased intake of sugars, it seems reasonable to conclude that advice relating to sugars intake is a relevant component of a strategy to reduce the high risk of overweight and obesity in most countries.” That is, it’s reasonable to advise people to cut down on their sugar consumption. 
     
    Findings from observational studies have been “more ambiguous,” though, with an association found between obesity and intake of sweetened beverages, but failing to show consistent correlations with consumption of sugary foods. Most such studies rely on self-reported data, however, and “it is likely that this has introduced bias, especially as underreporting of diet has been found to be more prevalent among obese people and it is sugar-rich foods that are most commonly underreported.” However, one can measure trace sucrose levels in the urine, which gives an objective measure of actual sugar intake and also excludes contributions from other sweeteners such as high fructose corn syrup. When researchers did this, they discovered that, indeed, sugar intake is not only associated with greater odds of obesity and greater waist circumference on a snapshot-in-time cross-sectional basis, but that was also seen in a prospective cohort study over time. “Using urinary sucrose as the measure of sucrose intake,” researchers found that “participants in the highest v. the lowest quintile [fifth] for sucrose intake had 54% greater risk of being overweight or obese.” 
     
    “Denying evidence that sugars are harmful to health has always been at the heart of the sugar industry’s defense.” But when the evidence is undeniable, like the link between sugar and cavities, it switches from denial to deflection, like trying to pull attention away from restricting intake to coming up with some kind of “vaccine against tooth decay.” We seem to have reached a similar point with obesity, with the likes of the Sugar Bureau switching from denial to deflection by commissioning research suggesting that obese individuals would not benefit from losing weight, a stance contradicted by hundreds of studies across four continents involving more than ten million participants. 
     
    For more on Big Sugar’s influence, check out Sugar Industry Attempts to Manipulate the Science. 
     
    You may also be interested in some of my other popular videos on sugar. See related videos below.

    Michael Greger M.D. FACLM

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  • The New Rule for Calories per Pound of Weight Loss  | NutritionFacts.org

    The New Rule for Calories per Pound of Weight Loss  | NutritionFacts.org

    You may lose a pound of fat by skipping just 10 calories a day or as many as 55, depending on whether you’re improving food quality or restricting food quantity. 
     
    If the 3,500 calories per pound of weight loss rule is bunk, what’s the alternative? To lose a pound of fat, how many fewer calories do you have to eat or how many more do you have to burn? That’s the topic of my video The New Calories per Pound of Weight Loss Rule. 
     
    There are validated mathematical models that take into account the dynamic changes that occur when you cut calories, such as the metabolic slowdown, and they’ve been turned into free online calculators you can use to make personalized estimates. For instance, one is the Body Weight Planner from the National Institutes of Health (http://bit.ly/NIHcalculator) and another is the Pennington Biomedical Research Center’s Weight Loss Predictor Calculator out of Louisiana State University (http://bit.ly/LSUcalculator). 
     
    The NIH Body Weight Planner has been found to be more accurate because the LSU model appears to overestimate the drop in physical activity, but they both have their own pluses and minuses. The NIH Body Weight Planner tells you how many calories you need to restrict and/or how much more you need to exercise to achieve a specific weight-loss goal by a specific date. If you click on the “Switch to Expert Mode” button, you can get a graph and exportable chart showing your day-to-day weight-loss trajectory. See below and at 1:15 in my video to see the Body Weight Planner. 

    For instance, if you are a middle-aged, sedentary, average-height woman who is obese at 175 pounds and wants to be closer to her ideal weight within a year, consuming 2,000 calories a day would prevent future weight gain and taking in about 1,400 calories a day would bring down your weight, and you could maintain that lower weight at 1,700 calories a day. If you also walked a mile a day, you’d have a little more calorie leeway.

    The LSU Weight Loss Predictor, however, doesn’t allow you to tweak physical activity, but its advantage is that you don’t have to choose a goal or time frame. Just put in different calorie changes, and it graphs out your expected course, as you can see in the graph below and at 2:00 in my video. 

    Is there an easy rule of thumb you can use? Yes. Every permanent ten-calorie drop in daily intake will eventually lead to about one pound of weight loss, though it takes about a year to achieve half the total weight change and around three years to completely settle into the new weight. So, cutting 500 calories a day can cause the 50-pound weight loss predicted by the 3,500-Calorie Rule, but that’s the total weight loss at which you plateau, not an annual drop, and it takes about three years to get there. A 500-calorie deficit would be expected to cause about a 25-pound weight loss in the first year, followed by an additional 25 pounds lost over years two and three, but that’s only if you can maintain the 500-calorie deficit, as you can see in the graph below and at 2:38 in my video.


    If you’re eating the same diet that led to the original weight problem but just in smaller servings, you should expect your appetite to rev up by about 45 calories per pound lost. So, if you were cutting 500 calories a day through portion control alone, even before you were down a dozen pounds, you’d feel so famished that you’d be driven to eat 500 more calories a day and your weight loss could vanish. For this reason, if you’re dead set on eating the same diet with the same foods, just in smaller quantities, you have to cut down an additional 45 calories per pound of desired weight loss to offset your hunger drive. 
     
    So, to take off that one pound, instead of consuming just 10 fewer calories a day using the 10 Calories per Pound Rule, you’d have to eat 10 fewer calories on top of the 45 fewer calories to account for the revving up of your appetite. Thus, it would be 10 + 45 = 55 fewer calories. Indeed, just by changing diet quantity and not quality, it takes 55 fewer calories per day to lose a pound, so that daily 500-calorie deficit would only net you about a 9-pound weight loss over time instead of 50 pounds. That’s why portion control methods can be such a frustrating failure for so many people. 
     
    If you missed my first two videos on calories per pound, check out The 3,500 Calorie per Pound Rule Is Wrong and The Reason Weight Loss Plateaus When You Diet. 
     
    I have loads of other weight-loss videos, which you can see here on the topic page, and there are gazillions more coming soon, based on my book How Not to Diet.

    Michael Greger M.D. FACLM

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  • Why Weight Loss Plateaus on Diets  | NutritionFacts.org

    Why Weight Loss Plateaus on Diets  | NutritionFacts.org

    What are the metabolic and behavioral adaptations that slow weight loss? 
     
    Thanks to millions of years of evolution hard-wiring us to survive scarcity, our body has compensatory survival mechanisms to defend against weight loss. When we start losing weight, we may unconsciously begin to move less as a “behavioral adaptation” to conserve energy. There are metabolic adaptations as well; our metabolism slows down. Every pound of weight loss may reduce our resting metabolic rate by seven calories a day. This may only translate to a few percent differences for most, but it can rapidly snowball for those who achieve massive weight loss. I discuss this phenomenon in my video The Reason Weight Loss Plateaus When You Diet.

    During one season of the television show The Biggest Loser, some of the contestants famously had their metabolic rates tracked. As you can see in the graphs below, above and beyond the hundreds of fewer calories it takes to just exist when more than a hundred pounds lighter (at 0:55 in my video), by the end of the season, their metabolic rates had slowed by an extra 500 calories a day (at 1:03 in my video). 

    What’s mind-blowing is that when they were retested six years later, they still had the 500-calorie-a-day handicap. So, the contestants had to cut 500 more calories than anyone else their size to maintain the same weight loss. No wonder the bulk of their weight loss was regained. As you can see in the graph below and at 1:23 in my video, most remained at least 10 percent lower than their starting weight, though. 

    Even a 7 percent drop has been shown to cut diabetes rates about in half, as seen in the graph below and at 1:31 in my video. Still, the metabolic slowing means you have to work that much harder than everyone else just to stay in place. Analyzing four seasons of The Biggest Loser minute-by-minute, researchers noted that 85 percent of the focus was on exercise rather than diet, though the exercise component accounted for less than half of the weight loss. Even six years after their season ended, the contestants had been maintaining an hour of daily, vigorous exercise, yet still regained most of the weight they had lost. Why? Because they had started eating more. They could have limited their exercise to just 20 minutes a day and still maintained 100 percent of their initial weight loss if they had just been able to keep their intake to less than 3,000 calories a day. That may not sound like much of a challenge, but weight loss doesn’t just slow your metabolism. It also boosts your appetite.

    If it were just a matter of your weight settling at the point at which your reduced caloric intake matches your reduced caloric output, it would take years for your weight loss to plateau. Instead, it often happens within six to eight months. You can see illustrative graphs below and at 2:34 and 2:43 in my video. You may know the drill: Start the diet, stick to the diet, then weight loss stalls six months later. What happened? Don’t blame your metabolism—that only plays a small part. Instead, you likely stopped sticking to your diet because your appetite went on a rampage. 

    Let’s break it down. If you cut 800 calories out of your daily diet—going from 2,600 calories a day down to 1,800, for instance—and your weight loss stalls after six months, what may have happened is, at the end of the first month, you think you’re still cutting 800 calories, but you may actually only be down about 600 calories a day. By month two, you may only be down about 500 calories, 300 by month three, and, by month six, you may only be eating 200 calories less than before you went on the diet. In other words, you may have inadvertently suffered an exponential increase in caloric intake over those six months. But, you may not even realize it because, by that time, your body may have ramped up your appetite by 600 calories. So, it still feels as if you are eating 800 calories less, but it’s actually only 200 fewer calories. Since an 800-calorie drop in intake may slow your metabolism and physical activity by about 200 calories a day, with no difference between calories in and calories out at six months, no wonder your weight loss grinds to a complete halt.

    The slow upward drift in caloric intake on a new diet is not because you got lazy. Once your appetite is boosted by 600 calories after dieting for a while, eating 200 fewer calories at the end is as hard as eating 800 fewer calories at the beginning. So, you can maintain the same disciplined level of willpower and self-control yet still end up stagnating. To prevent this from happening, you need to maintain the calorie deficit. How is that possible in the face of a ravenous appetite? 
     
    Hunger is a biological drive. Asking someone to eat smaller portions is like asking someone to take fewer breaths. You can white-knuckle it for a bit, but, eventually, nature wins out. That’s why I wrote How Not to Diet. There are foods that can counter the slowing of our metabolism and suppress our appetite, as well as ways of eating to counter the behavioral adaptation and even eat more food—yet still lose weight. 
     
    Due to “the ongoing slowing of metabolism and increased appetite associated with the lost weight,” sustained weight loss requires a persistent calorie deficit of 300 to 500 calories a day. This can be accomplished without reducing portion sizes simply by lowering the calorie density of meals, which can result in the rare combination of weight loss with both an increase in quality and even quantity of food consumed. (See the two graphs below and at 5:34 and 5:40 in my video.) The bottom line is that sustainable weight loss is not about eating less food. It’s about eating better food.

    In my previous video, I dive into how The 3,500 Calorie per Pound Rule Is Wrong. In that case, what’s The New Calories per Pound of Weight Loss Rule? Watch that video to find out. 
     
    My book How Not to Diet is all about weight loss and how to break the diet cycle. For more on weight loss, see related videos below.

    See the Weight Loss topic page for more relevant videos. 

    Michael Greger M.D. FACLM

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  • Debunking the 3,500-Calorie-per-Pound Rule  | NutritionFacts.org

    Debunking the 3,500-Calorie-per-Pound Rule  | NutritionFacts.org

    How many fewer calories do you have to eat every day to lose one pound of body fat? 

    The first surgical attempt at body sculpting was in 1921 on a dancer “who wanted to improve the shape of her ankles and knees.” The surgeon apparently scraped away too much tissue and tied the stitches too tight, resulting in necrosis, amputation, and the first recorded malpractice suit in the history of plastic surgery. Liposuction is much safer today, killing only about 1 in 5,000 patients, mostly from unknown causes, such as throwing a clot into your lung or perforating your internal organs. You can see a “Cause of Death” chart below and at 0:37 in my video The 3,500 Calorie per Pound Rule Is Wrong. 

    Liposuction currently reigns as the most popular cosmetic surgery in the world, and its effects are indeed only cosmetic. A study published in the New England Journal of Medicine assessed obese women before and after having about 20 pounds of fat sucked out of their bodies, resulting in a nearly 20 percent drop in their total body fat. Normally, if you lose even just 5 to 10 percent of your body weight in fat, you get significant improvements in blood pressure, blood sugars, inflammation, cholesterol, and triglycerides. But liposuction sucks. None of those benefits materialized even after massive liposuction, which suggests that the problem is not subcutaneous fat, the fat under our skin. The metabolic insults of obesity arise from the visceral fat, the fat surrounding or even infiltrating our internal organs, like the fat marbling our muscles and liver. The way you lose that fat, the dangerous fat, is to take in fewer calories than you burn. 
     
    Anyone who’s seen The Biggest Loser television programs knows that with enough caloric restriction and exercise, hundreds of pounds can be lost. Similarly, there are cases in the medical literature of what some refer to as “super obesity.” In one case, a man lost a massive amount of weight “largely without professional help and without surgery” and kept it off for years. He dropped 374 pounds, losing about 20 pounds a month by cycling two hours a day and reducing his daily intake to 800 calories, which is down around what some prisoners got at concentration camps in World War II. 
     
    Perhaps “America’s most celebrated weight loss” seen on television was Oprah’s. She pulled out a wagon full of fat, representing the 67 pounds she had lost on a very-low-calorie diet. How many calories did she have to cut to achieve that weight loss within four months? If you consult with leading nutrition textbooks or refer to trusted authorities like the Mayo Clinic, you’ll learn the simple weight loss rule: 1 pound of fat equals 3,500 calories. Quoting from the Journal of the American Medical Association, “A total of 3500 calories equals 1 pound of body weight. This means if you decrease (or increase) your intake by 500 calories daily, you will lose (or gain) 1 pound per week. (500 calories per day × 7 days = 3500 calories.)” 
     
    It’s the simple weight-loss rule that is simply not true. 
     
    The 3,500-calorie rule can be traced back to a paper published in 1958. The author noted that since fatty tissue in the human body is 87 percent fat, a pound of body fat would have about 395 grams of pure fat. Multiplying that by nine calories per gram of fat gives you that “3,500 calories per pound” approximation. The fatal flaw that leads to “dramatically exaggerated” weight-loss predictions is that the 3,500-calorie rule fails to take into account the fact that changes in the Calories-In side of the energy-balance equation automatically lead to changes in the Calories-Out side—for example, metabolic adaption, the slowing of metabolic rate that accompanies weight loss. That’s one reason weight loss plateaus. 
     
    Imagine a sedentary, 30-year-old woman of average height who weighs 150 pounds. According to the 3,500-calorie rule, if she cuts 500 calories out of her daily diet, she’d lose a pound a week or 52 pounds a year. In three years, she would vanish. She’d go from 150 pounds to -6. Obviously, that doesn’t happen. Instead, as you can see in the graph below and at 4:33 in my video, in the first year, she’d likely lose 32 pounds, not 52. Then, after a total of three years, she’d probably stabilize at about 100 pounds. This is because it takes fewer calories to exist as a thin person.  


    Part of it is “simple mechanics”: More energy is required to move a heavier mass, in the same way a Hummer requires more fuel than a compact car. Think how much more effort it would take to just get up from a chair, walk across the room, or climb a few stairs if you were carrying a 50-pound backpack. Even when you’re at rest, sound asleep, there’s simply less of your body to maintain as you lose weight. Every pound of fat tissue lost may mean one less mile of blood vessels through which your body has to pump blood every minute. So, the basic upkeep and movement of thinner bodies take fewer calories. As you lose weight by eating less, you end up needing less. That’s what the 3,500-calorie rule doesn’t take into account. 
     
    Imagine it another way: A 200-pound man starts consuming 500 more calories a day, maybe by drinking a large soda or eating two donuts. According to the 3,500-calorie rule, in ten years, he’d weigh more than 700 pounds. That doesn’t happen because, the heavier he is, the more calories he burns just by existing. If you’re 100 pounds overweight, it’s as if there’s a skinny person inside you trying to walk around balancing 13 gallons of oil or lugging around a sack filled with 400 sticks of butter. As you can see in the graph below and at 6:13 in my video, it takes about two donuts’ worth of extra energy just to live at 250 pounds, so that’s where you’d plateau if you kept it up. Given a certain calorie excess or deficit, weight gain or weight loss is a curve that flattens out over time, rather than a straight line up or down. 


    Nevertheless, the 3,500-calorie rule continues to crop up, even in obesity journals. Public health researchers used it to calculate how many pounds children might lose every year if, for example, fast-food kids’ meals swapped in apple slices for french fries. You can see the “Counting Calories in Kids’ Meals” graphic below and at 6:39 in my video. 

    They figured that two meals a week could add up to about four pounds a year. The actual difference, National Restaurant Association–funded researchers were no doubt delighted to point out, would probably add less than half a pound—ten times less than the 3,500-calorie rule would predict, as you can see below and at 7:06 in my video. That original article was subsequently retracted. 

     
    The 3,500 Calorie per Pound Rule Is Wrong is the first of 14 videos that are part of my fasting series, about which I did two webinars. The videos are on NutritionFacts.org, or you can get them all now in a digital download at Intermittent Fasting. You may also be interested in my webinars on Fasting and Disease Reversal and Fasting and Cancer.

    Other videos in this series are included in related videos below. 
     
    Check out some other popular videos on weight loss.

    I also recently tackled the ketogenic diet.

    Michael Greger M.D. FACLM

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  • Keto Diets and Diabetes  | NutritionFacts.org

    Keto Diets and Diabetes  | NutritionFacts.org

    Ketogenic diets are put to the test for diabetes reversal. 
     
    As you can see at the start of my video Does a Ketogenic Diet Help Diabetes or Make It Worse?, ketogenic diets can lower blood sugars better than conventional diets. So much so, in fact, that there is a keto product company that claims ketogenic diets can “reverse” diabetes. However, they are confusing the symptom (high blood sugars) with the disease (carbohydrate intolerance). People with diabetes can’t properly handle carbohydrates, and this manifests as high blood sugars. Clearly, if you stick to eating mostly fat, your blood sugars will stay low, but you may be actually making the underlying disease worse at the same time. 
     
    We’ve known for nearly a century that if you put people on a ketogenic diet, their carbohydrate intolerance can skyrocket within just two days. Below and at 0:46 in my video, you can see a graph from the study showing the blood sugar response two days after eating sugar. On a high-carb diet, blood sugar response is about 90 mg/dL. But, the blood sugar response to the same amount of sugar after a high-fat diet is about 190 mg/dL, nearly double. The intolerance to carbohydrates skyrocketed on a high-fat diet. 

    After one week on an 80 percent fat diet, you can quintuple your blood sugar spike in reaction to the same carb load compared to a week on a low-fat diet, as you can see in the graph below and at 1:12 in my video. 

    Even a single day of excessive dietary fat intake can do it, as you can see in the graph below and at 1:26 in my video. If you’re going in for a diabetes test, having a fatty dinner the night before can adversely affect your results. Just one meal high in saturated fat can make carbohydrate intolerance, the cause of diabetes, worse within four hours. 


    Given enough weight loss by any means, whether from cholera or bariatric surgery, type 2 diabetes can be reversed, but a keto diet for diabetes may not just be papering over the cracks, but actively throwing fuel on the fire. 
     
    I’ve been trying to think of a good metaphor. It’s easy to come up with things that just treat the symptoms without helping the underlying disease, like giving someone with pneumonia aspirin for their fever instead of antibiotics. However, a keto diet for diabetes is worse than that because it may treat the symptoms while actively worsening the disease. It may be more like curing the fever by throwing that pneumonia patient out into a snow bank or “curing” your amputated finger by amputating your hand. One of the co-founders of masteringdiabetes.org suggested it’s like a CEO who makes their bad bottom line look better by borrowing tons of cash. The outward numbers look better, but on the inside, the company is just digging itself into a bigger hole. 
     
    Do you remember The Club, that popular car anti-theft device that attaches to the steering wheel and locks it in place so the steering column can only turn a few inches? Imagine you’re in a car at the top of a hill with the steering wheel locked. Then, the car starts rolling down the hill. What do you do? Imagine there’s also something stuck under your brake pedal. The keto-diet equivalent response to this situation is who cares if you’re barreling down into traffic with a locked steering wheel and no brakes—just stick to really straight deserted roads without any stop signs or traffic lights. If you do that, problem solved! The longer you go, the more speed you’ll pick up. If you should hit a dietary bump in the road or start to veer off the path, the consequences could get more and more disastrous over time. However, if you stick to the keto straight and narrow, you’ll be a-okay! In contrast, the non-keto response would be to just unlock the steering wheel and dislodge whatever’s under your brake. In other words, fix the underlying problem instead of just whistling past—and then into—the graveyard. 
     
    The reason keto proponents claim they can “reverse” diabetes is they can successfully wean type 2 diabetics off their insulin. That’s like faith-healing someone out of the need for a wheelchair by making them stay in bed the rest of their life. No need for a wheelchair if you never move. Their carbohydrate intolerance isn’t gone. Their diabetes isn’t gone. In fact, it could be just as bad or even worse. Type 2 diabetes is reversed when you are weaned off insulin while eating a normal diet like everyone else. Then and only then do you not have diabetes anymore. A true diabetes reversal diet, as you can see below and at 4:58 in my video, is practically the opposite of a ketogenic diet: getting diabetics off their insulin within a matter of weeks by eating more than 300 grams of carbs a day! 
    The irony doesn’t stop there. One of the reasons people with diabetes suffer such nerve and artery damage is due to an inflammatory metabolic toxin known as methylglyoxal, which forms at high blood sugar levels. Methylglyoxal is the most potent creator of advanced glycation end products (AGEs), which are implicated in degenerative diseases—from Alzheimer’s and cataracts to kidney disease and strokes, as you can see below and at 5:31 in my video. 

    You get AGEs in your body from two sources: You can eat them preformed in your diet or make them internally from methylglyoxal if you have high blood sugar levels. On a keto diet, one would expect high exposure to preformed AGEs, since they’re found concentrated in animal-derived foods high in fat and protein, but we would expect less internal, new formation due to presumably low levels of methylglyoxal, given lower blood sugars from not eating carbs. Dartmouth researchers were surprised to find more methylglyoxal! As shown in the graph below and at 6:11 in my video, a few weeks on the Atkins diet led to a significant increase in methylglyoxal levels. Those in active ketosis did even worse, doubling the level of this glycotoxin in their bloodstream. 

    It turns out that high sugars may not be the only way to create this toxin, as you can see below and at 6:24 in my video. One of the ketones you make on a ketogenic diet is acetone (known for its starring role in nail polish remover). Acetone does more than just make keto dieters fail breathalyzer tests, “feel queasy and light-headed, and develop what’s been described as ‘rotten apple breath.’” Acetone can oxidize in the blood to form acetol, which may be a precursor for methylglyoxal.

    That may be why keto dieters can end up with levels of this glycotoxin as high as those with out-of-control diabetes, which can cause the nerve damage and blood vessel damage you see in diabetics. That’s another way keto dieters can end up with a heart attack. The irony of treating diabetes with a ketogenic diet may extend beyond just making the underlying diabetes worse, but by mimicking some of the disease’s dire consequences. 

    This is part of a seven-video series on keto, which you can find in related videos below.

    I also recently tackled diabetes.

    Michael Greger M.D. FACLM

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  • Muscle Shrinkage and Bone Loss on Keto Diets?  | NutritionFacts.org

    Muscle Shrinkage and Bone Loss on Keto Diets?  | NutritionFacts.org

    Ketogenic diets have been found to undermine exercise efforts and lead to muscle shrinkage and bone loss. 
     
    An official International Society of Sports Nutrition position paper covering keto diets notes the “ergolytic effect” of keto diets on both high- and low-intensity workouts. Ergolytic is the opposite of ergogenic. Ergogenic means performance-boosting, whereas ergolytic means performance-impairing. 
     
    For nonathletes, ketosis may also undermine exercise efforts. Ketosis was correlated with increased feelings of “perceived exercise effort” and “also significantly correlated to feelings of ‘fatigue’ and to ‘total mood disturbance,’” during physical activity. “Together, these data suggest that the ability and desire to maintain sustained exercise might be adversely impacted in individuals adhering to ketogenic diets for weight loss.” 
     
    You may recall that I’ve previously discussed that shrinkage of measured muscle mass among CrossFit trainees has been reported. So, a ketogenic diet may not just blunt the performance of endurance athletes, but their strength training as well. As I discuss in my video Keto Diets: Muscle Growth and Bone Density, study participants performed eight weeks of the battery of standard upper and lower body training protocols, like bench presses, pull-ups, squats, and deadlifts, and there was no surprise. You boost muscle mass—unless you’re on a keto diet, in which case there was no significant change in muscle mass after all that effort. Those randomized to a non-ketogenic diet added about three pounds of muscle mass, whereas the same amount of weight lifting on the keto diet tended to subtract muscle mass by about 3.5 ounces on average. How else could you do eight weeks of weight training and not gain a single ounce of muscle on a ketogenic diet? Even keto diet advocates call bodybuilding on a ketogenic diet an “oxymoron.” 
     
    What about bone loss? Sadly, bone fractures are one of the side effects that disproportionately plague children placed on ketogenic diets, along with slowed growth and kidney stones. Ketogenic diets may cause a steady rate of bone loss as measured in the spine, presumed to be because ketones are acidic, so keto diets can put people in what’s called a “chronic acidotic state.” 
     
    Some of the case reports of children on keto diets are truly heart-wrenching. One nine-year-old girl seemed to get it all, including osteoporosis, bone fractures, and kidney stones, then she got pancreatitis and died. Pancreatitis can be triggered by having too much fat in your blood. As you can see in the graph below and at 2:48 in my video, a single high-fat meal can cause a quintupling of the spike in triglycerides in your bloodstream within hours of consumption, which can put you at risk for inflammation of the pancreas.  

    The young girl had a rare genetic disorder called glucose transporter deficiency syndrome. She was born with a defect in ferrying blood sugar into her brain. That can result in daily seizures starting in infancy, but a ketogenic diet can be used as a way to sneak fuel into the brain, which makes a keto diet a godsend for the 1 in 90,000 families stricken with this disorder.

    As with anything in medicine, it’s all about risks versus benefits. As many as 30 percent of patients with epilepsy don’t respond to anti-seizure drugs. Unfortunately, the alternatives aren’t pretty and can include brain surgery that implants deep electrodes through the skull or even removes a lobe of your brain. This can obviously lead to serious side effects, but so can having seizures every day. If a ketogenic diet can help with seizures, the pros can far outweigh the cons. For those just choosing a diet to lose weight, though, the cost-benefit analysis would really seem to go the other way. Thankfully, you don’t need to mortgage your long-term health for short-term weight loss. We can get the best of both worlds by choosing a healthy diet, as I discussed in my video Flashback Friday: The Weight Loss Program That Got Better with Time.
     
    Remember the study that showed the weight loss was nearly identical in those who had been told to eat the low-carb Atkins diet for a year and those told to eat the low-fat Ornish diet, as seen below and at 4:18 in my video? The authors concluded, “This supports the practice of recommending any diet that a patient will adhere to in order to lose weight.” That seems like terrible advice. 

    There are regimens out there like “The Last Chance Diet which consisted of a low-calorie liquid formula made from leftover byproducts from a slaughterhouse [that] was linked to approximately 60 deaths from cardiovascular-related events.” An ensuing failed lawsuit from one widower laid the precedent for the First Amendment protection for those who produce deadly diet books. 

    It’s possible to construct a healthy low-carb diet or an unhealthy low-fat one—a diet of cotton candy would be zero fat—but the health effects of a typical low-carb ketogenic diet like Atkins are vastly different from a low-fat plant-based diet like Ornish’s. As you can see in the graph below and at 5:26 in my video, they would have diametrically opposed effects on cardiovascular risk factors in theory, based on the fiber, saturated fat, and cholesterol contents of their representative meal plans. 

    And when actually put to the test, low-carb diets were found to impair artery function. Over time, blood flow to the heart muscle itself is improved on an Ornish-style diet and diminished on a low-carb one, as shown below and at 5:44 in my video. Heart disease tends to progress on typical weight-loss diets and actively worsens on low-carb diets, but it may be reversed by an Ornish-style diet. Given that heart disease is the number one killer of men and women, “recommending any diet that a patient will adhere to in order to lose weight” seems irresponsible. Why not tell people to smoke? Cigarettes can cause weight loss, too, as can tuberculosis and a meth habit. The goal of weight loss is not to lighten the load for your pallbearers. 

     
    For more on keto diets, see my videos on the topic. Interested in enhancing athletic performance? Check out the related videos below. 

    Michael Greger M.D. FACLM

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