3 UNDYING MYTHS OF EXERCISE AND NUTRITION

Published in Issue #5 | Summer 2016

by Vic Tringali, MS, CSCS

While science has debunked many myths of diet and exercise, some remain up in the air, causing both athletes and generally health-conscious gym-goers to bicker over their accuracy. But no matter how preposterous they may be, some myths seem to be holding strong today. 

Here are three physiological fallacies that continue to fly in the face of science.

 # 1 Eating more frequently speeds up metabolism. 

The idea that eating frequent, small meals throughout the day encourages weight loss has been carved deeply into mainstream diet dogma for years. Increasing meal frequency has been touted as an energy booster and jump starter of metabolism. But regardless of what you may have heard from your local bro-scientist, most clinical research fails to support those claims.

When we eat, our bodies use energy to digest the macronutrients in our meals, fat, protein, and carbohydrates. This energy is what is referred to in science as the thermic effect of food (TEF). The TEF causes a temporary increase in basal metabolic rate. In theory, eating more frequently should stimulate this increase in metabolic rate more often, leading to an increase of calories expended throughout the course of the day. However the impact of TEF is proportional to the size of a meal. Meaning the calories expended during the digestion of three 1000-calorie meals will be the same amount expended with six 500-calorie meals of the same proportion of macronutrients. 

Most data collected from research examining the effect of meal frequency show no significant difference in weight loss, or fat loss, between high or low meal frequencies. In 2011, the International Society of Sports Nutrition released a position paper on meal frequency, and based on a large body of cited data, the paper concludes that increased meal frequency does not affect body composition or resting metabolic rate.

In fact, one study which examined the effect of meal frequency on insulin response, resting metabolic rate , and perceived hunger found that low meal frequencies were associated with increased resting metabolism and appetite control, not only questioning the benefits of frequent eating, but suggesting that eating fewer, larger meals may actually aid in weight control. 

This doesn’t mean that eating more frequent meals is bad. For some individuals eating more than three times a day may be more appropriate. For example, an athlete who can’t satisfy his/her macronutrient and calorie requirements in 3 meals may benefit by eating more frequently. Higher level athletes may also benefit by paying special attention to the timing of pre and post-workout nutrition in order to optimize training and recovery.

# 2 Fasted cardio exercise leads to greater fat loss.

Research has shown that the breakdown of fatty acids during exercise is 23% greater in a pre-fed condition. Armed with what appears to be a “slam-dunk” of exercise science, fasted cardio is often advocated by bodybuilders and weight loss enthusiasts. 

However, the benefits of fasted cardio may not be as significant as they first appear in the literature. In a 1999 study, trained subjects who exercised at 50 percent of their max heart rate, demonstrated no difference in the amount of fat oxidized–regardless of whether the subjects had eaten. Only after 90 minutes of exercise did fasted subjects begin to yield a favorable result in the amount of fat oxidation. What this means is you would need to exercise for a minimum of 90 minutes to derive an additional benefit.

Secondly, what most fitness aficionados fail to realize is the amount of fat broken down during fasted exercise exceeds the amount that can be used for fuel. Consequently, the free fatty acids that are not oxidized become re-esterfied in adipose (fat) tissue, thereby negating any intended benefits.

Another important consideration is that performing cardio in a fasted state has been shown to increase the breakdown of muscle tissue. Studies show that training in a fasted state substantially increases the amount of tissue proteins burned for energy during exercise. Since lean muscle mass is the major determinant of metabolism, sacrificing lean tissue would be detrimental to overall metabolic rate and total caloric expenditure.

Finally, a 2014 study by Schoenfeld and colleagues concluded that “body composition changes associated with aerobic exercise in conjunction with a hypocaloric diet are similar regardless whether or not an individual is fasted prior to training.” 

# 3 Eating carbs at night will make you fat.

The asinine belief may be lingering on due to the advice of misguided mainstream media “gurus” who claim to know their way around energy metabolism. The truth is scientific research has found no evidence that a difference exists between the storage of carbs eaten at lunch or at 10pm. The bigger picture when it comes to weight gain or weight maintenance is energy balance. If we consume the same amount of calories we expend via our daily metabolic activity, we’ll maintain a steady weight. Since your body is in a constant state of energy storage and energy release, as long as you aren’t overeating, the energy that’s stored tonight will be mobilized tomorrow. So overeating carbs and calories in general, causes weight gain, and not the time of day they’re consumed.

Can avoiding late-night carbs work? Of course. Except it’s nothing more than a default method of cutting calories. Cutting back on the same amount of carbs earlier in the day is generally just as effective.

The biggest problem for most people who eat late at night is that they aren’t just eating a postponed dinner, they’re consuming extra calories in the form of snacks, usually enjoyed in front of a TV or computer and they aren’t necessarily “healthy” choices. What’s more, late night snacking usually leads to out of control portions eaten straight out of a box or bag, which research has shown leads to eating more.

Furthermore, if you’re an athlete and train at night, it may be especially important to eat carbs later into the evening. Rather than increasing fat stores, these carbs will be used to replenish muscles and aid recovery. 

Bottom line, if you’re making healthy, wholesome food choices throughout the entire day, staying active and maintaining a neutral energy balance, there’s no need to put your kitchen on lockdown after 8pm.

Train Smart and Good Luck!

 

Laura Olsen

Houston, TX