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Tag: LDL cholesterol

  • 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

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    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. 

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    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

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    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. 



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    Michael Greger M.D. FACLM

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  • The Safety of Keto Diets  | NutritionFacts.org

    The Safety of Keto Diets  | NutritionFacts.org

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    What are the effects of ketogenic diets on nutrient sufficiency, gut flora, and heart disease risk? 

    Given the decades of experience using ketogenic diets to treat certain cases of pediatric epilepsy, a body of safety data has accumulated. Nutrient deficiencies would seem to be the obvious issue. Inadequate intake of 17 micronutrients, vitamins, and minerals has been documented in those on strict ketogenic diets, as you can see in the graph below and at 0:14 in my video Are Keto Diets Safe?. 

    Dieting is a particularly important time to make sure you’re meeting all of your essential nutrient requirements, since you may be taking in less food. Ketogenic diets tend to be so nutritionally vacuous that one assessment estimated that you’d have to eat more than 37,000 calories a day to get a sufficient daily intake of all essential vitamins and minerals, as you can see in the graph below and at 0:39 in my video. 


    That is one of the advantages of more plant-based approaches. As the editor-in-chief of the Journal of the American Dietetic Association put it, “What could be more nutrient-dense than a vegetarian diet?” Choosing a healthy diet may be easier than eating more than 37,000 daily calories, which is like putting 50 sticks of butter in your morning coffee. 
     
    We aren’t just talking about not reaching your daily allowances either. Children have gotten scurvy on ketogenic diets, and some have even died from selenium deficiency, which can cause sudden cardiac death. The vitamin and mineral deficiencies can be solved with supplements, but what about the paucity of prebiotics, the dozens of types of fiber, and resistant starches found concentrated in whole grains and beans that you’d miss out on? 
     
    Not surprisingly, constipation is very common on keto diets. As I’ve reviewed before, starving our microbial self of prebiotics can have a whole array of negative consequences. Ketogenic diets have been shown to “reduce the species richness and diversity of intestinal microbiota,” our gut flora. Microbiome changes can be detected within 24 hours of switching to a high-fat, low-fiber diet. A lack of fiber starves our good gut bacteria. We used to think that dietary fat itself was nearly all absorbed in the small intestine, but based on studies using radioactive tracers, we now know that about 7 percent of the saturated fat in a fat-rich meal can make it down to the colon. This may result in “detrimental changes” in our gut microbiome, as well as weight gain, increased leaky gut, and pro-inflammatory changes. For example, there may be a drop in beneficial Bifidobacteria and a decrease in overall short-chain fatty acid production, both of which would be expected to increase the risk of gastrointestinal disorders. 
     
    Striking at the heart of the matter, what might all of that saturated fat be doing to our heart? If you look at low-carbohydrate diets and all-cause mortality, those who eat lower-carb diets suffer “a significantly higher risk of all-cause mortality,” meaning they live, on average, significantly shorter lives. However, from a heart-disease perspective, it matters if it’s animal fat or plant fat. Based on the famous Harvard cohorts, eating more of an animal-based, low-carb diet was associated with higher death rates from cardiovascular disease and a 50 percent higher risk of dying from a heart attack or stroke, but no such association was found for lower-carb diets based on plant sources.  
     
    And it wasn’t just Harvard. Other researchers have also found that “low-carbohydrate dietary patterns favoring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favored plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain bread, were associated with lower mortality…” 
     
    Cholesterol production in the body is directly correlated to body weight, as you can see in the graph below and at 3:50 in my video. 

    Every pound of weight loss by nearly any means is associated with about a one-point drop in cholesterol levels in the blood. But if we put people on very-low-carb ketogenic diets, the beneficial effect on LDL bad cholesterol is blunted or even completely neutralized. Counterbalancing changes in LDL or HDL (what we used to think of as good cholesterol) are not considered sufficient to offset this risk. You don’t have to wait until cholesterol builds up in your arteries to have adverse effects either; within three hours of eating a meal high in saturated fat, you can see a significant impairment of artery function. Even with a dozen pounds of weight loss, artery function worsens on a ketogenic diet instead of getting better, which appears to be the case with low-carb diets in general.  

    For more on keto diets, check out my video series here. 

    And, to learn more about your microbiome, see the related videos below.

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    Michael Greger M.D. FACLM

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