This was taken directly from leangains. I hesitate to post it seeing as I recommend 8 out of 10 of these 'myths' on a daily basis to people, but I am always willing to keep an open mind, see things in a different light, and most important, listen to science!
I did not post this in my IF thread since it's not all related to fasting, but rather to dieting in general. Enjoy the read and feel free to comment! This should get a lot of people questioning things and researching for themselves:
Top Ten Diet Myths Debunked
by Martin Berkhan
Everyone who learns about nutrition through the usual channels, be it fitness magazines, mainstream diet books and forums, gets cursed with the prevailing belief system of what constitutes a good diet.
Though specific dietary recommendations vary slightly depending on who you listen to, there are many common denominators and "rules" that you are told you must adhere to. Call it broscience, incompetence or ignorance, same thing. We've all been there and we've all followed these rules. Led like sheep, not knowing better. Trusting that those we listen to knew what they were talking about. While these dietary myths run rampant in the bodybuilding and fitness community, you'll find that many are being endlessly propagated in the mainstream as well.
Upon closer scrutiny, the great majority lack scientific basis. They are born out out of half-truths, faulty conclusions drawn from poorly conducted studies or created when a study gets cited out of context.
Sometimes, what's claimed is even in exact opposition to what really occurs at a physiological level. Many people believe that alcohol is fattening, more so than any other macronutrient. Yet, if you look at how inefficiently the body converts ethanol to fat, you'll find that it's completely backwards. I talked about this in "The Truth about Alcohol, Fat Loss and Muscle Growth". Also note how the proposed negative effect of alcohol on muscle growth doesn't even exist in the scientific literature.
You'll see similar examples in this article. For example, in short-term fasting, it's often claimed that metabolic rate slows down - yet looking at the studies, the opposite is true.
The myths I'll debunk today are being kept alive by:
1. Repetition. Repeat something often enough and it becomes the truth. If everyone is saying the same thing, it must be true. No need to look into it and think for yourself. The fact that bodybuilders and fitness celebrities keep propagating these myths doesn't help either. Most people reason that if these people do it, it must be great. Unfortunately, bodybuilders and fitness celebrities might just be one of the last people on earth you should listen to if you want objective and accurate opinions in nutrition.
2. Commercial forces. For example, the supplement industry benefits greatly from people believing that frequent feedings provide a metabolic advantage. People don't have time to eat six cooked meals a day. Instead, they turn to meal replacement powders, shakes and protein bars. The cereal and grain industry benefits by preaching about the virtues of breakfast for weight control, health and fat loss. There's no commercial incentive in telling people that they would do just fine with three squares a day.
3. Few people have the knowledge or interest needed to interpret the scientific evidence and draw their own conclusions. In order to do this you would need an academic background that included critical examination of studies and study methodology as part of the learning process.
However, an academic background, or an extensive education in nutrition or physiology, seems to correlate very poorly with truthfulness and objectivity in the field of dietetics in my experience. The advice and claims I have seen made by many RDs (Registered Dietitians) has been so shamelessly wrong that I put little stock in anything they have to say. The same goes for many "diet gurus" and so-called health experts with a solid list of academic credentials.
That people who should know better keep repeating the same myths is somewhat puzzling and strange. Perhaps they lose interest in keeping up with research. What we know today is a bit different from what we knew twenty years ago after all. Or maybe they're afraid that their credibility would be questioned if they change the advice they have been giving for years. I'm not sure. I've been thinking about it quite a bit. But I digress. Back to the topic.
The top ten fasting myths debunked
The dietary recommendations and advice given in mainstream media and most fora will have you believe that fasting is a hazardous practice. On top of wrecking your metabolism, you should expect ravenous hunger, fat gain, muscle loss, and severe mental impairment. Or so you are told.
Needless to say, people who are introduced to Leangains and the intermittent fasting diet concept have many fears that will make them think twice before embracing it. Fears grounded in years of a dietary indoctrination based on faulty ideas and lies. We've all been there.
I've listed the ten most common fasting and diet myths that exist to make people resistant to intermittent fasting. I've explained why they're wrong and linked out to references and other resources for those who would like to read a more detailed review of the issues. I've also listed their origins, or what I believe to be their origins.
I've dealt with each myth many times before on this site but it would be good to have everything in one place. Even if you've been following me for a while, you'll find some new information here I haven't discussed in the past. It's a long read but it'll be worth your while.
1. Myth: Eat frequently to "stoke the metabolic fire".
Truth
Each time you eat, metabolic rate increases slightly for a few hours. Paradoxically, it takes energy to break down and absorb energy. This is the Thermic Effect of Food (TEF). The amount of energy expended is directly proportional to the amount of calories and nutrients consumed in the meal.
Let's assume that we are measuring TEF during 24 hours in a diet of 2700 kcal with 40% protein, 40% carbohydrate and 20% fat. We run three different trials where the only thing we change is the the meal frequency.
A) Three meals: 900 kcal per meal.
B) Six meals: 450 kcal per meal.
C) Nine meals: 300 kcal per meal.
What we'd find is a different pattern in regards to TEF. Example "A" would yield a larger and long lasting boost in metabolic rate that would gradually taper off until the next meal came around; TEF would show a "peak and valley"-pattern. "C" would yield a very weak but consistent boost in metabolic rate; an even pattern. "B" would be somewhere in between.
However, at the end of the 24-hour period, or as long as it would take to assimilate the nutrients, there would be no difference in TEF. The total amount of energy expended by TEF would be identical in each scenario. Meal frequency does not affect total TEF. You cannot "trick" the body in to burning more or less calories by manipulating meal frequency.
Further reading: I have covered the topic of meal frequency at great length on this site before.
The most extensive review of studies on various meal frequencies and TEF was published in 1997. It looked at many different studies that compared TEF during meal frequencies ranging from 1-17 meals and concluded:
"Studies using whole-body calorimetry and doubly-labelled water to assess total 24 h energy expenditure find no difference between nibbling and gorging".
Since then, no studies have refuted this. For a summary of the above cited study, read this research review by Lyle McDonald.
Earlier this year, a new study was published on the topic. As expected, no differences were found between a lower (3 meals) and higher meal (6 meals) frequency. Read this post for my summary of the study. This study garnered some attention in the mass media and it was nice to see the meal frequency myth being debunked in The New York Times.
Origin
Seeing how conclusive and clear research is on the topic of meal frequency, you might wonder why it is that some people, quite often RDs in fact, keep repeating the myth of "stoking the metabolic fire" by eating small meals on a frequent basis. My best guess is that they've somehow misunderstood TEF. After all, they're technically right to say you keep your metabolism humming along by eating frequently. They just missed that critical part where it was explained that TEF is proportional to the calories consumed in each meal.
Another guess is that they base the advice on some epidemiological studies that found an inverse correlation between high meal frequency and body weight in the population. What that means is that researchers may look at the dietary pattern of thousands individuals and find that those who eat more frequently tend to weigh less than those who eat less frequently. It's important to point out that these studies are uncontrolled in terms of calorie intake and are done on Average Joes (i.e. normal people who do not count calories and just eat spontaneously like most people).
There's a saying that goes "correlation does not imply causation" and this warrants further explanation since it explains many other dietary myths and fallacies. Just because there's a connection between low meal frequencies and higher body weights, doesn't mean that low meal frequencies cause weight gain. Those studies likely show that people who tend to eat less frequently have:
* Dysregulated eating patterns; the personality type that skips breakfast in favor of a donut in the car on the way to work, undereat during the day, and overeat in the evening. They tend to be less concerned with health and diet than those who eat more frequently.
* Another feasible explanation for the association between low meal frequencies and higher body weight is that meal skipping is often used as a weight loss strategy. People who are overweight are more likely to be on a diet and eat fewer meals.
The connection between lower meal frequency and higher body weight in the general population, and vice versa, is connected to behavioral patterns - not metabolism.
2. Myth: Eat smaller meals more often for hunger control.
Truth
Given the importance of finding the most favorable meal pattern for hunger and appetite control, there's a surprising scarcity of studies on the topic. The most widely cited study is one where obese males were fed 33% of their daily calorie requirement ("pre-load") in either one single meal or five meals before being allowed to eat ad libitum five hours later (meaning as much as they desired).
A: One single meal was consumed. 5 hours later they were free to eat as much as they desired, "buffet"-style.
B: Same setup as above. However, the single meal was now split into five smaller meals, which were consumed every hour leading up to the ad libitum meal.
The results showed that subjects undergoing "A" ate 27% more calories when given the ad libitum meal. The same setup was used by the same researchers on lean males and showed similar results. However, upon closer scrutiny it's clear how little real world application those results have. The macrocomposition of the pre-load was 70% carbs, 15% fat and 15% protein; given as pasta, ice cream and orange juice. The situation created was highly artificial and abnormal. Who sits around nibbling on pasta and ice cream, sipping orange juice, every hour leading up to a regular meal?
The latest research, performed under conditions that more closely resemble a real-world scenario, shows the opposite result. In this study, three high-protein meals lead to greater fullness and appetite control when compared to six high-protein meals. You can read my summary of the study here: Three Meals Superior for Appetite Control.
There's no doubt that meal frequency is highly individual. However, absolute statements claiming smaller meals are superior for hunger and appetite control are untrue and are based on studies using methods that greatly differed from real-world meal patterns. Current research with a normal meal pattern and protein intakes that are closer to what can be seen in a typical non-retarded diet, suggests superior appetite control when eating fewer and larger meals.
Origin
This myth might have originated from the limited data from studies on meal frequencies and appetite control. It's also likely that it's another case of mistaking correlation for causation from studies and meal frequencies and higher body weights; if people who eat more often weigh less, then it must mean they can control their hunger better, etc.
3. Myth: Eat small meals to keep blood sugar levels under control.
Truth
According to legions of diet and health "experts," eating small meals every so often will help you avoid hunger pangs, provide you with stable energy throughout the day and keep you mentally sharp. Contrary to what many people seem to believe, blood sugar is extremely well-regulated and maintained within a tight range in healthy people. It does not swing wildly up and down like a chimpanzee on meth and it doesn't plummet from going a few hours without food. Or even a full day without food. Or a week without food for that matter.
People seem to believe they will suffer severe hunger and mental impairment from not eating every so often. Consider for a second the evolutionary consequences for survival if this was true. Given that regular periods of fasting, even famine, was a natural part of our past, do you think we'd be here today if we were unable to function when obtaining food was most critical? I have seen healthy young males, bodybuilders nonetheless, complain of lethargy and mental haze if they didn't get to eat for a few hours. It's completely absurd. But I digress...
Maintaining blood sugar is of very high priority and we have developed efficient pathways that will make it happen even under extreme conditions. If you were to fast for 23 hrs and then go for a 90 min run at 70-75% VO2max, your blood sugar after the run would be identical to the same run performed in the fed state. It would take no less than three days or 84 hours of fasting to reach blood sugar levels low enough to affect your mental state; and this is temporary, as your brain adapts to the use of ketones. During 48 hours of fasting, or severe calorie deprivation, blood sugar is maintained within a normal range no measure of cognitive performance is negatively affected.
For more on blood sugar, read my review of Eat Stop Eat Expanded Edition, which includes a relevant excerpt. Also, keep in mind that the above cited studies are all performed under conditions that are much more extreme than the fasting protocol I, or Brad Pilon, recommends.
What about blood sugar and hunger? Blood sugar is one of many short-term feedback mechanisms used to regulate hunger and the notion which exists to say that low blood sugar may cause hunger is correct. Low just means lower range. This is subject to numerous confounders, such as your habitual diet, energy intake and genetics. Most importantly perhaps, it's subject to entrained meal patterns, regulated by ghrelin and other metabolic hormones. In essence, this means that blood sugar follows the meal pattern you are used to. This is relevant for those who fear blood sugar issues and hunger from regular periods of fasting, as it serves to explain why people can easily adapt to regular periods of fasting without negative effects.
Origin
Not sure how people came to believe that skipping a meal would dumb them down. There is some truth to blood sugar and hunger, but this is often taken out of context. There's no need to eat regularly to "maintain" blood sugar as it maintains itself just fine and adapts to whatever meal pattern you choose.
4. Myth: Fasting tricks the body into "starvation mode".
Truth
Efficient adaptation to famine was important for survival during rough times in our evolution. Lowering metabolic rate during starvation allowed us to live longer, increasing the possibility that we might come across something to eat. Starvation literally means starvation. It doesn't mean skipping a meal not eating for 24 hours. Or not eating for three days even. The belief that meal skipping or short-term fasting causes "starvation mode" is so completely ridiculous and absurd that it makes me want to jump out the window.
Looking at the numerous studies I've read, the earliest evidence for lowered metabolic rate in response to fasting occurred after 60 hours (-8% in resting metabolic rate). Other studies show metabolic rate is not impacted until 72-96 hours have passed (George Cahill has contributed a lot on this topic).
Seemingly paradoxical, metabolic rate is actually increased in short-term fasting. For some concrete numbers, studies have shown an increase of 3.6% - 10% after 36-48 hours (Mansell PI, et al, and Zauner C, et al). This makes sense from an evolutionary perspective. Epinephrine and norepinephrine (adrenaline/noradrenaline) sharpens the mind and makes us want to move around. Desirable traits that encouraged us to seek for food, or for the hunter to kill his prey, increasing survival. At some point, after several days of no eating, this benefit would confer no benefit to survival and probably would have done more harm than good; instead, an adaptation that favored conservation of energy turned out to be advantageous. Thus metabolic rate is increased in short-term fasting (up to 60 hours).
Again, I have choosen extreme examples to show how absurd the myth of "starvation mode" is - especially when you consider that the exact opposite is true in the context of how the term is thrown around.
Origin
I guess some genius read that fasting or starvation causes metabolic rate to drop and took that to mean that meal skipping, or not eating for a day or two, would cause starvation mode.
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Originally Posted by terraj
