08-11-2011, 05:38 AM
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the six small meals a day bullshit
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".
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.
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.