Thursday, October 21, 2010

Top Ten Fasting Myths Debunked (Major Update Nov 4th)

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Or "Top Ten Diet Myths Debunked". That would have fit almost as well. Ok, so in retrospect, I think I screwed up on the title. Many myths just happened to be connected to intermittent fasting (meal frequency, breakfast skipping, etc.). Well, live and learn.

November 4th Addendum: Section added at the end of the article.

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.


5. Myth: Maintain a steady supply of amino acids by eating protein every 2-3 hours. The body can only absorb 30 grams of protein in one sitting.


Truth

Whenever you hear something really crazy you need to ask yourself if it makes sense from an evolutionary perspective. It's a great way to quickly determine if something may be valid or if it's more likely a steaming pile of horseshit. This myth is a great example of the latter. Do you think we would be here today if our bodies could only make use of 30 grams of protein per meal?

The simple truth is that more protein just takes a longer time to digest and be utilized. For some concrete numbers, digestion of a standard meal is still incomplete after five hours. Amino acids are still being released into your bloodstream and absorbed into muscles. You are still "anabolic." This is a fairly standard "Average Joe"-meal: 600 kcal, 75 g carbs, 37 g protein and 17 g fat. Best of all? This was after eating pizza, a refined food that should be quickly absorbed relatively speaking.

Think about this for a second. How long do you think a big steak, with double the protein intake of the above example, and a big pile of veggies would last you? More than 10 hours, that's for sure. Meal composition plays an important role in absorption speed, especially when it comes to amino acids. Type of protein, fiber, carbohydrates and prior meals eaten all affect how long you'll have amino acids released and being taken up by tissues after meals.

Origin

I think this "30 grams of protein"-nonsense started to circulate after a classic study from 1997 by Boirie and colleagues. "Slow and fast dietary proteins differently modulate postprandial protein accretion" was the first study to quantify the absorption rate of whey and casein protein and gave birth to the concept of fast and slow protein. After that, whey protein came to be known for it's ability to rapidly elevate amino acids in the blood stream and casein for it's ability to create a sustained release of amino acids. Whey was anabolic and casein anti-catabolic.

Given that 30 grams of whey protein was absorbed within 3-4 hours, I guess some people believed that meant 30 grams of protein can only be used in one sitting. Or that you had to eat every 3-4 hours to stay "anabolic." Unfortunately, people missed a few facts that made these findings irrelevant to real-world scenarios. First of all, this study looked at the absorption rate of whey protein in the fasted state. On it's own, and with no meals eaten beforehand, 30 grams of whey protein is absorbed within a mere 3-4 hours. With meals eaten earlier in the day, or if you'd consume a whey shake after a meal, absorption would be much slower.

Second of all, whey protein is the fastest protein of all and digests at 10 g/hour. Casein is much slower; in Boirie's study, the casein protein was still being absorbed when they stopped the experiment 7 hours later. Most whole food proteins are absorbed at a rate of 3-6 grams an hour. Add other macronutrients to that and they'll take longer.


One of my clients, showing symptoms of profound catabolism by impaired protein absorption and daily 16 hour periods of fasting.

Further reading:

"Is There a Limit to how Much Protein the Body can Use in a Single Meal?" by Alan Aragon.

What Are Good Sources of Protein? – Speed of Digestion Part 1
What Are Good Sources of Protein? – Speed of Digestion Part 2


6. Myth: Fasting causes muscle loss.


Truth

This myth hinges on people's belief it's important to have a steady stream of amino acids available to not lose muscle. As I explained earlier, protein is absorbed at a very slow rate. After a large high-protein meal, amino acids trickle into your blood stream for several hours.

No studies have looked at this in a context that is relevant to most of us. For example, by examining amino acid appearance in the blood and tissue utilization of amino acids after a large steak, veggies and followed up with some cottage cheese with berries for dessert. That's easily 100 grams of protein and a typical meal for those that follow the Leangains approach. We are left to draw our own conclusions based on what we know; that a modest amount of casein, consumed as a liquid on an empty stomach is still releasing amino acids after 7 hours. With this in mind it's no stretch to assume that 100 grams of protein as part of a mixed meal at the end of the day would still be releasing aminos for 16-24 hours.

Few studies has examined the effects of regular fasting on muscle retention and compared it to a control diet. None of them are relevant to how most people fast and some are marred by flaws in study design and methodology. Like this study which showed increased muscle gain and fat loss, with no weight training or change in calorie intake, just by changing meal frequency. While I would love to cite that study as proof for the benefits of intermittent fasting, body composition was measured by BIA, which is notoriously imprecise.

Only in prolonged fasting does protein catabolism become an issue. This happens when stored liver glycogen becomes depleted. In order to maintain blood glucose, conversion of amino acids into glucose must occur (DNG: de novo glucogenesis). This happens gradually and if amino acids are not available from food, protein must be taken from bodily stores such as muscle. Cahill looked at the contribution of amino acids to DNG after a 100 gram glucose load. He found that amino acids from muscle contributed 50% to glucose maintenance after 16 hours and almost 100% after 28 hours (when stored liver glycogen was fully depleted). Obviously, for someone who eats a high protein meal before fasting, this is a moot point as you will have plenty of aminos available from food during the fast.

Origin

An example of severe exaggeration of physiological and scientific fact, not relevant to anyone who's not undergoing prolonged fasting or starvation.


7. Myth: Skipping breakfast is bad and will make you fat.


Truth

Breakfast skipping is associated with higher body weights in the population. The explanation is similar to that of lower meal frequencies and higher body weights. Breakfast skippers have dysregulated eating habits and show a higher disregard for health. People who skip breakfast are also more likely to be dieting, thus by default they are also likely to be heavier than non-dieters. Keep in mind that most people who resort to breakfast skipping are not the type that sit around and read about nutrition. They are like most people dieting in a haphazard manner. The type to go on a 800 calorie-crash diet and then rebound, gaining all the weight (and then some) back.

Sometimes, an argument is made for eating breakfast as we are more insulin sensitive in the morning. This is true; you are always more insulin sensitive after an overnight fast. Or rather, you are always the most insulin sensitive during the first meal of the day. Insulin sensitivity is increased after glycogen depletion. If you haven't eaten in 8-10 hours, liver glycogen is modestly depleted. This is what increases insulin sensitivity - not some magical time period during the morning hours. Same thing with weight training. Insulin sensitivity is increased as long as muscle glycogen stores aren't full. It doesn't disappear if you omit carbs after your workout.

Origin

First of all, we have the large scale epidemiological studies showing an association with breakfast skipping and higher body weights in the population. One researcher from that study, commenting on the association with breakfast skipping or food choices for breakfast, said:

"These groups appear to represent people 'on the run,' eating only candy or soda, or grabbing a glass of milk or a piece of cheese. Their higher BMI would appear to
support the notion that 'dysregulated' eating patterns are associated with obesity, instead of or in addition to total energy intake per se."

Kellogg's and clueless RDs love to cite them over and over again, so people are lead to believe that breakfast has unique metabolic and health-related benefits. In reality, these studies just show breakfast eaters maintain better dietary habits overall.

Other studies frequently cited claiming that breakfast is beneficial for insulin sensitivity are all marred with methodological flaws and largely uncontrolled in design.

In one widely cited study, subjects were entrusted to eat most meals in free-living conditions. The breakfast skipping group ate more and gained weight, which affected health parameters negatively.

From the abstract: "Reported energy intake was significantly lower in the EB period (P=0.001), and resting energy expenditure did not differ significantly between the 2 periods." EB = eating breakfast. In essence, people who ate breakfast could control their energy intake better for the rest of the day. They didn't gain any weight but the breakfast skipping group did. Fat gain always affects insulin sensitivity and other health parameters negatively. Thus what people took this to mean is that breakfast is healthy and improves insulin sensitivity. Which isn't at all what the study showed.


8. Myth: Fasting increases cortisol.


Truth

Cortisol is a steroid hormone that maintains blood pressure, regulates the immune system and helps break down proteins, glucose and lipids. It's a hormone that's gotten quite a bad rep in the fitness and health community but we have it for a reason. The morning peak in cortisol makes us get out of bed and get going. A blunted morning cortisol peak is associated with lethargy and depression. Cortisol is elevated during exercise, which helps mobilize fats, increase performance and experience euphoria after and during workouts. Trying to suppress acute elevations of cortisol during exercise, or the normal diurnal rhythm, is foolish. Chronically elevated levels of cortisol, resulting from psychological and/or physiological stress, is another thing and unquestionably bad for your health; it increases protein breakdown, appetite and may lead to depression.

Short-term fasting has no effect on average cortisol levels and this is an area that has been extensively studied in the context of Ramadan fasting. Cortisol typically follows a diurnal variation, which means that its levels peak in the morning at around 8 a.m. and decline in the evenings. What changes during Ramadan is simply the cortisol rhythm, average levels across 24 hours remain unchanged.

In one Ramadan study on rugby players, subjects lost fat and retained muscle very well. And they did despite training in a dehydrated state, without pre-workout or post-workout protein intake, and with a lower protein intake overall nonetheless. Quoting directly from the paper:

"Body mass decreased significantly and progressively over the 4-week period; fat was lost, but lean tissue was conserved..."

"...Plasma urea concentrations actually decreased during Ramadan, supporting the view that there was no increase of endogenous protein metabolism to compensate for the decreased protein intake."

In one study on intermittent fasting, the fasting group even saw "significant decrease in concentrations of cortisol." However, this study should be taken with a grain of salt as it had some flaws in study design.

In conclusion, the belief that fasting increases cortisol, which then might cause all kinds of mischief such as muscle loss, has no scientific basis whatsoever.

Origin

Prolonged fasting or severe calorie restriction causes elevated baseline levels of cortisol. This occurs in conjunction with depletion of liver glycogen, as cortisol speeds up DNG, which is necessary to maintain blood sugar in absence of dietary carbs, protein, or stored glycogen. Again, it seems someone looked at what happens during starvation and took that to mean that short-term fasting is bad.


9. Myth: Fasted training sucks. You'll lose muscle and have no strength.


Truth

A large body of research on sports performance during Ramadan concludes that aerobic activities, such as 60 minutes of running, has a small yet significant negative impact on performance. A very large confounder here is dehydration, as Ramadan fasting involves fluid restriction. That said, anaerobic performance, such as weight training, is much less impacted.

However, more relevant and telling studies, which don't involve fluid restriction, show that strength and lower intensity endurance training is unaffected - even after 3.5 days of fasting. New research on fasted training supports this. If you read my review of that study, you'll see that the only parameter the fed group did better on was improvements in V02max, which is likely explained by the fact that the carbs allowed them to train at a higher intensity. However, note the other interesting results obtained in the fasted group. Also note that a review I did of another fasted endurance training study showed no negative effect of fasting on endurance or VO2max (quite the contary in fact). This can be explained by the lower intensity.

In conclusion, training in the fasted state does not affect your performance during weight training, which is what most people reading this are interested in. However, training in a completely fasted state is still not something I recommend for optimal progress. Research is quite clear on the benefits of pre-workout and post-workout protein intake for maximizing protein synthesis. For this reason, I suggest supplementing with 10 g BCAA prior to fasted training.



Another weak and frail physique. No wonder. Andreaz does most of his training fasted. Also worth mentioning, Richard Nikoley trained almost exclusively fasted (and basically doubled his deadlift, while losing fat).

Read more about pre-workout protein and fasted training here: "Pre-workout Protein Boosts Metabolism" and "Fasted Training Boosts Muscle Growth?".

Also read: Early Morning Fasted Training

Specific protocols for fasted training are covered in "The Leangains Guide".

Origin

It's actually intuitive that a big pre-workout meal would help with performance, so it's not surprising that people have their doubts about training on an empty stomach.


10. Myth: "Eat breakfast like a king, lunch a queen, dinner like a pauper."


Truth

Also connected to this saying, is the belief that you should reduce carbs in the evening as they will be less likely to be stored as fat. While this might sound good on paper, there's nothing to support it and a lot that shows it to be wrong.

The strongest argument against this are the numerous studies available on body composition and health after and during Ramadan fasting. This meal pattern of regular nightly feasts has a neutral or positive effect on body fat percentage and other health parameters. This is quite an extreme and telling example. People literally gorge on carbs and treats in the middle of the night to no ill effect. And yet, in the bizarre world of bodybuilding and fitness, people worry whether it's OK to eat 50 grams of carbs in their last meal.

If the scientific data on Ramadan fasting aren't enough, there are plenty of other studies showing no effect on weight loss or weight gain from eating later in the day.

In one study comparing two meal patterns, which involved one group eating more calories earlier in the day and one group eating most calories later in the day, more favorable results were found in the group eating large evening meals. While those who ate more in the AM lost more weight, the extra weight was in the form of muscle mass. The late evening eaters conserved muscle mass better, which resulted in a larger drop in body fat percentage.

Origin

Just like breakfast skipping is associated with higher body weights in the general population, you will find associations with late night eating and higher body weights. If you have been reading this far, you'll understand the logical fallacy of saying that late night eating must cause weight gain based on such studies. People who engage in late night eating, such as snacking in front of the TV, are likely to weigh more than others. It's not the fact that they are eating later in the day that causes weight gain, it's their lifestyle. No controlled studies show larger evening meals affect body composition negatively in comparison to meals eaten earlier in the day.

Sometimes studies on shift workers are cited to claim that late night eating is bad. These are all uncontrolled (in terms of calorie intake) and observational studies confounded by the fact that shift work has an independent and negative effect on some health parameters like glucose tolerance and blood lipids. Keep this in mind. Context is always relevant.

While I normally don't cite studies on animals, Science Daily featured an article dispelling the late-night eating myth based on findings on rhesus monkeys. It's worth citing since monkeys are metabolically closer to humans than rodents.

I should have written this article post a long time ago. Would have saved me tons of time.

If you found this worthwhile reading, I'd appreciate if you could refer those unlucky people, who have been mislead into believing some of the junk that's out there, to this article. Based on my own and others' experiences, these false beliefs lead many into an obsessive dietary pattern, which can do a lot of harm to your physical and psychological well-being. Let's try to put an end to that and save people from such misery.



November 4th Addendum


First of all, I appreciate the support and help with spreading this article around. I’ve received dozens of emails from people who’ve told me that this was a great eye opener for them; a seed for a new way of critical thinking – in place of blind acceptance of these dubious claims that are often made. So for those who have assisted me in the fight against broscience and diet myths, thanks. Good karma will come your way.

As I read through the article I didn’t find anything that needed to be clarified further or worth changing. Well, nothing that would change the conclusions at least. Since I like this stuff I could easily devote a full article to each one of the different myths and delve deeper into the nuances and methodological problems that plague some of the widely cited data from which they are born. But this article is already long enough as it is.

However, I do have a few addendums I’d like to make. I’ve added them here, so those who didn’t read the article when it first appeared have to sift through it again.


1. Myth: Eat frequently to "stoke the metabolic fire".


One of the most ridiculous arguments against a low (or should I say normal?) meal frequency is the one of sumo wrestlers eating habits. Since sumo wrestlers eat two times a day it must be the best way to get fat and exactly what you shouldn’t be doing for fat loss, or so the logic goes. I wouldn’t have blamed anyone for bringing this argument into the discussion 34 years ago – because it was actually what some researchers believed at that time.

The methods and logic used to arrive at such a conclusion was completely retarded. For example, as a “control group” they used healthy Japanese males weighing 105-130 lbs eating three meals a day. Brilliant. It’s fair to say that nutritional science and research wasn't exactly stellar at that time (Ancel Keys anyone?) but this “study” was terrible even by medieval standards. Yes, it must be meal frequency that’s to blame. Never mind the 5000+ calories consumed on a daily basis.

The traditional dish consumed by sumo wrestlers, Chankonabe, is actually not bad at all in terms of calorie density and food composition. Seems it’s even popular among thin Japanese women. However, since Chankonabe is so deeply entrenched into sumo culture, wrestlers will only count a dish served with Chankonabe as a meal. Snacks eaten in between the two daily Chankonabe meals, which are events that are treated like rituals of great importance, simply aren’t considered as meals or reported as such. This quote is pretty telling: “…I eat hamburgers and foods I purchase at convenience stores as snacks.” (From "Sumo meal now what the petite eat.")

I found the tidbit about Chankonabe tradition interesting, but it's also one very big confounder that was not considered in that old worthless study. The reported mean intake of the wrestlers, 5100-5600 kcal is quite a lot for a 230 lb male (average weight in the study,) but considering the daily training sumo wrestlers go through, it’s certainly not a mind boggling amount. It’s safe to say that calorie intake was probably significantly higher given the exclusion of snacks. There was no tracking of the sumo wrestlers diet by the researchers. It's amazing that this study passed its peer review.


5. Myth: Maintain a steady supply of amino acids by eating protein every 2-3 hours. The body can only absorb 30 grams of protein in one sitting.


I forgot to mention one critical study that often comes up in the context of a high meal frequency being beneficial when dieting. In “Effects of meal frequency on body composition during weight control in boxers.” it was found that boxers eating two meals a day on a 1200-calorie diet lost more muscle than the six-meal-group. There are many errors with this conclusion. Lyle McDonald summarized them nicely:

“In this study, boxers were given either 2 or 6 meals per day with identical protein and calories and examined for lean body mass lost; the 2 meal per day group lost more lean body mass (note: both groups lost lean body mass, the 2 meal per day group simply lost more). Aha, higher meal frequency spares lean body mass. Well, not exactly.

In that study, boxers were put on low calories and then an inadequate amount of liquid protein was given to both groups and the meals were divided up into 2 or 6 meals. But the study design was pretty crappy and I want to look at a few reasons why I think that.

First and foremost, a 2 vs. 6 meal per day comparison isn’t realistic. As discussed in The Protein Book, a typical whole food meal will only maintain an anabolic state for 5-6 hours, with only 2 meals per day, that’s simply too long between meals and three vs. six meals would have been far more realistic (I would note that the IF’ing folks are doing just fine not eating for 16 hours per day).

Additionally is the use of a liquid protein that confounds things even more. Liquids digest that much more quickly than solid foods so the study was basically set up to fail for the low meal frequency group. They were given an inadequate amount of rapidly digesting liquid protein too infrequently to spare muscle loss. But what if they had been given sufficient amounts of solid protein (e.g. 1.5 g/lb lean body mass) at those same intervals? The results would have been completely different.

As discussed in The Protein Book in some detail, meal frequency only really matters when protein intake is inadequate in the first place. Under those conditions, a higher meal frequency spares lean body mass. But when protein intake is adequate in the first place (and again that usually means 1.5 g/lb lean body mass for lean dieters), meal frequency makes no difference. And that’s why the boxer study is meaningless so far as I’m concerned. An inadequate amount of liquid protein given twice per day is nothing like how folks should be dieting in the first place.”

From: “Meal Frequency and Mass Gains.”

So in summary, a low calorie intake coupled with an inadequate amount of liquid protein. Liquid protein is rapidly absorbed. This would leave the low meal frequency-group without dietary protein available in between meals, causing DNG, de novo gluconeogenesis, of endogenous protein stores (muscle). The large energy deficit and leanness of the boxers are also factors to consider.

None of this is apparent if you look at the abstract of the study; no protein intake or protein type is mentioned. Details that are critical to know in this context.

I should also point out that I was wrong about the origins of this myth which several people have pointed out. This is what Lyle McDonald wrote in comments:

“The 30 g/meal thing has been around for decades, much older than the 1997 paper. A few gut hunches on where it came from.

1. Marketing: I base this on the fact that the value has changed over the years. When Met-RX sold products with 30 grams protein, 30 g/meal was the cutoff. When they moved to 42 g/meal, 42 grams was the cutoff. Weider probably did it before then.

2. Bodybuilders looking to rationalize their desire to eat lots of mini-meals after the fact. So take an average male bodybuilder, 180 lbs eating 1 g/lb who has decided that 6 meals/day is optimal and....

3. Even there, I think Gironda had written this. It probably came out of some bullshit paper in the 50's that was taken out of context and just got repeated long enough to become dogmatic truth.”

So that’s that.


7. Myth: Skipping breakfast is bad and will make you fat.


A new study on breakfast and health came out a few weeks ago. It brings nothing new to the table; the conclusions drawn are similar to that of older studies that found correlations between body weight and breakfast skipping.

However, since it’s such a beautiful example of everything that is wrong with epidemiology, I will devote a separate post to it, instead of dissecting it in this article, which is long enough as it is. I will have a detailed analysis up soon. Not because I believe that I need to make my point any clearer, but because it will be a lesson in critical thinking.


My biggest frustration


Unfortunately, while this article might have opened a few people’s eyes, I fear that it might be for naught when it comes to the great majority. At least for the mainstream crowd who prefers anecdotes and muscle magazines over science-based articles such as this one. Just have a look at the comments in this thread on comedian Joe Rogan’s forum:

“He 'debunked' those ideas by his own logic and his interpretation of various studies. It wasn't very convincing.”

The only reason it wasn’t convincing enough for this clown was that he could not understand the abstracts my links pointed to. That’s assuming he even took the time to read the article (likelihood: 0.01%).

However, I’m not surprised. The Average Joe (or should I say "Average Bro"?) seems to think everything is up for “interpretation,” which is a load of bullshit. There are objective truths to be found if you look for them. But finding them takes time, requires some effort. Most people shy away from it. Getting spoon-fed is more comfortable. That's OK, because not everyone wants to read some basic nutrition and physiology textbooks. But at least be humble enough to understand that your opinion is not one that you have formed on your own.

As i see it, the problem is twofold in the sense that outliers, the majority of which have severe methodological flaws, often get all of the attention (i.e. the boxers study). The other problem is that many accepted “truths” are based on the conclusions drawn from correlational studies (i.e. meal frequency and breakfast skipping). This is what trickles down and is presented to the mainstream and they swallow it; hook, line, and sinker.

And even then, when the mass media for once debunks a myth, some people just cover their ears and go "lalalala," saying things like:

“I just read it. I'm still not buying it though.”

From the Joe Rogan forum thread, in response to the New York Times article that debunked the meal frequency myth. What a sheep.

There are plenty of more comments along those lines. Makes for some half-decent entertainment. For someone stranded on an abandoned island that is. Note that no one presented evidence that contradicted this article and the conclusions I have presented. Critique is fine but not when it cannot be backed by anything else than gym lore. Fortunately, some people are smarter than that.

This is my biggest frustration with this industry. Those that scream loud enough win - the supplement companies, mass media "health experts" and diet gurus with Magic Pills and Secret Methods to sell.

Someone who is unfamiliar with my background may easily mistake me and my writings for the latter and believe I have presented evidence that would somehow favor my methods, which I have not. This is unfortunate but understandable since almost everyone else in this industry tends to do it. It leads to much confusion as laypersons think everyone is trying to sell them something. For them, finding objective facts is like looking for a needle in a haystack.

But remember: never once have I said, or claimed, that I believe everyone needs to convert to intermittent fasting - or even that it is proven to be superior to a regular healthy diet. The research surrounding intermittent fasting is very interesting but it's too early to draw any definitive conclusions.

I am still of the opinion that the best diet is the one you can stick to in the long term. However, the decision should be based on personal preference and not neurotic adherence to a diet built on faulty and bad science.

201 comments:

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Jay said...

I used to think that IF was bullshit. To be honest, i had to fast for a bloodtest (16 hours) and i searched for the benefits and i stumbled into the greatness of it. Now ive just started on the journey! I feel good so far! :)

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My name is Martin Berkhan and I work as a nutritional consultant, magazine writer and personal trainer.

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