7 Common Nutrition Myths
There are no shortages of myths in the field of Nutrition. Today we’re going to run-through 7 of the most common myths within the field of nutrition.
1. Fat makes you fat! - This is one of the most pervasive and longstanding myths in the field of nutrition. Indeed, the existence of the Atkins diet, which places no restrictions on fat intake, should be evidence enough of the fallacy in this myth. Say what you will about the value, or lackthereof, of the Atkins diet, there is little doubt that it has remained popular since the 1970’s because of its efficacy in promoting weight loss.
So why does this myth persist then? Probably because of the focus on calories in the field of nutrition. Fat contains 9 calories/gram, as opposed to the 4 calories afforded by protein and carbohydrates. Unfortunately, as we’ll discuss in a subsequent myth, weight regulation is far more complex than just calories.
There are at LEAST two reasons why fat is not particularly fattening in comparison to carbohydrate:
I. fat has minimal, if any, effect on the anabolic hormone insulin (2)
II. fat doesn’t seem to elicit the addictive opioid response like that of sweet carbohydrates (3)
It is important to clarify that in the context of a high-carbohydrate diet, like that of the standard American diet, high-fat intake likely is deleterious, due to the combinatorial effect of high-calorie fat WITH high insulin stimulation from carbohydrates (insulin is the primary storage hormone in the body, which causes calories to be stored rather than burned)(2).
2. Eating small frequent meals throughout the day is best - It has become very common to recommend small frequent meals in order to prevent low blood sugar, increase metabolic rate, and reduce appetite. However, a 2014 analysis of the literature showed no compelling association after removal of one particularly suggestive trial (3). Furthermore, another review (4) showed that the opposite was true; small frequent meals led to increased hunger. Conversely, a 2011 analysis (5) did find an association with reduced appetite. However, their analysis did not find any corroboration of the assertion that small frequent meals would increase metabolic rate. Finally, studies which actually measure 24-hour whole-body energy expenditure do not show any beneficial effect of small frequent meals (6). Unfortunately, the vast majority of the studies investigating this idea are either poorly controlled and suffer from very small sample size.
The practical advice with regard to meal size and frequency would be to self-experiment. If you find that it does help you control appetite or improves your energy levels, then great, keep going!
3. Skipping breakfast will cause you to gain weight - Nutrition professionals often plead with their clients to “start the day off with a good breakfast,” to “jumpstart metabolism.” But are these statements backed by the scientific literature?
Not so much. A 2014 analysis of the literature (8) found pretty inconclusive results. As the authors write, “While it is widely believed that breakfast skipping leads to weight gain, there are few experimental studies which support this notion (8).”
So, similar to the practical advice for myth #2, if you prefer not eating breakfast and don’t find that you overcompensate by overeating for the rest of the day, then keep doing it! It may be a perfectly reasonable way of reducing calorie consumption and inducing weight loss, but self-experimentation is key.
4. High-protein diets are bad for kidneys - The next two myths pertain to “high” protein intakes. So before we begin, let’s just go over a few facts regarding the current state of protein recommendations in the U.S. First of all, the Institute of Medicine (IOM) determined their guidelines for the “recommended daily intake (RDI)” at 0.8 g/kg body weight for adults (10). It’s important to note though, that this is the amount they calculated to prevent deficiency, in 97.5% of the adult population. However, the amount needed to achieve optimal muscle and bone health may not be met by that intake (11). Furthermore, according to the IOM, the risk of adverse effects of protein intake at the upper level they’ve set (35%) is thought to be low (12).
Now back to our protein myths. Many dietitians believe that high-protein intake is damaging to kidney health, citing concerns of increased kidney filtration rate (13). However, as was previously stated, there is - as of 2015 - very little evidence of any harm, including to kidneys, from high-protein consumption (13). Furthermore, because of the self-limiting nature of protein (due to its satiating effects), the concern over high protein intake for healthy individuals seems unfounded.
*We would be remiss not to mention that high-protein diets ARE indeed dangerous for individuals with preexisting kidney dysfunction.
5. High-protein diets are bad for bone health - High protein consumption has been shown in numerous trials to actually improve calcium absorption in the intestines (14,15,16,17). In addition, it is well established that dietary protein increases IGF-1 levels (18), which itself has been shown to have a positive effect on bone health (10). Furthermore, a higher protein diet consumed for only 10 days has been shown to significantly lower circulating levels of a hormone called parathyroid hormone, which breaks down bone to release calcium for other cells, compared to a lower protein diet (15). To recap, protein enhances calcium absorption, reduces bone-degradation, and through IGF-1 indirectly stimulates bone health. And we haven’t even mentioned the role of protein in facilitating muscle growth, which then promotes improved bone density!
6. A calorie is a calorie is a calorie - Okay, this actually isn’t a myth; it’s true. A calorie is a very specific unit of energy; they are, indeed, all the same. However, the interpretation of this common phrase inside and outside of the nutrition community is somewhat flawed, and thus worth spending some time on.
This view has led many to believe that they can have the same weight loss success eating nothing but pizza (hypothetically) as a nutrient-dense whole-foods diet. If only human physiology were so simple! Unfortunately there are other aspects of foods, outside of their calorie content, that affect the way your body expends energy and influences hunger and satiety.
As an example, carbohydrate foods with a high glycemic index have a propensity to stimulate a large insulin spike which, again, will tend to drive more calories into storage - this is likely a predominant reason why type 2 diabetics that give themselves insulin injections throughout the day tend to gain fat. In fact, as further evidence of this, it is important to rotate insulin injection sites on the body to avoid large fat deposits in one small area! (18).
In addition, some argue that low-level vitamin and mineral deficiencies lead to hunger and cravings (19). This makes sense theoretically, however, empirical evidence is scant to date.
Suffice it to say, different foods influence hormones differently, and these hormones affect a myriad of appetite and calorie-regulating physiological processes (2). Our female readers are likely to find this to be quite obvious, as monthly hormonal changes in women often lead to specific food cravings.
7. Weight loss from a low-carb diet is only water - Among the common myths about low-carb diets is that the weight loss they induce comes from water instead of body fat. There is some truth here regarding increased water loss. however, this phenomenon will not persist for long, as it is largely a consequence of the depletion of stored glycogen (stored carbohydrate) in the initial adaptation phase of the diet - glycogen is stored with water and so water is excreted when glycogen stores are reduced. In a cross-over trial (20), for instance, participants lost 2.02 kg, with body water-weight not changing significantly and lean mass tending to increase, albeit insignificantly (+0.43 kg, p>0.2). The fact is, if there is any significant water-loss at all, it will only persist for a few days, with any subsequent weight loss being almost entirely of fat (assuming adequate protein consumption)
- Tanenbaum J. Delayed Gratification: Why it Took Everybody So Long to Acknowledge that Bacteria Cause Ulcers. J Young Invest. 2005. http://www.jyi.org/issue/delayed-gratification-why-it-took-everybody-so-long-to-acknowledge-that-bacteria-cause-ulcers/.
- Smith CM, Marks AD, Lieberman MA, Marks DB, Marks DB. Marks' basic medical biochemistry: A clinical approach. Philadelphia: Lippincott Williams & Wilkins; 2005.
- Mysels DJ, Sullivan MA. The relationship between opioid and sugar intake: review of evidence and clinical applications. J Opioid Manag. 2010; 6(6): 445-452.
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- Perrigue MM, Drewnowski A, Wang CY, Neuhouser ML. Higher Eating Frequency Does Not Decrease Appetite in Healthy Adults. J Nutr. 2015; pii: jn216978.
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- McCrory MA.Meal skipping and variables related to energy balance in adults: a brief review, with emphasis on the breakfast meal. Physiol Behav. 2014; 134: 51-54.
- Correia JC, Locatelli L, Golay A. How to lose weight effectively and in a sustainable manner: a review of current topics. Rev Med Suisse. 2015; 11(467): 689-690, 692-694.
- Cuenca-Sánchez M, Navas-Carrillo D, Orenes-Piñero. Controversies surrounding high-protein diet intake: satiating effect and kidney and bone health. Adv Nutr. 2015; 6(3): 260-266.
- Wolfe RR. Protein Summit: consensus areas and future research. Am J Clin Nutr 2008; 87: 1582S–3S.
- Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrates, fiber, fat, protein and amino acids (macronutrients). Washington (DC): National Academies Press; 2002.
- Friedman AN. High-protein diets: potential effects on the kidney in renal health and disease. Am J Kidney Dis 2004; 44: 950–62.
- Kerstetter JE, O’Brien KO, Caseria DM, Wall DE, Insogna KL. The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. J Clin Endocrinol Metab 2005; 90: 26–31.
- Kerstetter JE, Caseria DM, Mitnick ME, Ellison AF, Gay LF, Liskov TA, Carpenter TO, Insogna KL. Increased circulating concentrations of parathyroid hormone in healthy, young women consuming a protein-restricted diet. Am J Clin Nutr 1997; 66: 1188–96.
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