Diet Mythbusters: The Truth About Metabolism, Workout, Weight and Health


Myth #1: Workout “rewards”

“Rewarding” yourself for a good, intense workout is usually a self-defeating behavior. A few seconds of indulgence in a high-calorie treat can easily undo the hour or more of cardio you just struggled through. Many dieters manage not to lose weight, or even gain weight, because of the bad habit of treating themselves after a workout. And the reward is usually disproportionate to the activity. In a 2010 University of Ottawa study, 16 people in the healthy weight range walked on treadmills until they had burned 300 calories. When asked to estimate how much they burned, some guessed 896 calories.

The good news is that, “being fit can have psychological effects,” says Todd Hagobian, Ph.D., an assistant professor of kinesiology at Cal Poly. “Regular exercise may increase your desire to consume a better diet—and shed pounds.”

So, keep an eye on how many calories you’ve burned during a workout and track your treat’s calorie content accordingly. One tactic for getting the most fullness out of the least calories is to eat an abundance of low-cal foods packed with protein and/or fiber. This can include beans, oatmeal, fruits, and vegetables.

Myth #2: Exercise doesn’t help you lose weight

This idea is ridiculous. However, it is not uncommon to hear about someone who has undergone a strenuous training program and wound up gaining a few pounds. There is a lot of research that shows that exercise is key in keeping off weight. In addition to the obvious calorie-burning rewards, regular exercisers pay better attention to their bodies’ needs. Regular workouts also help maintain a better body tissue ratio (muscle to fat) and lower the risk of developing certain diseases.

A Cochrane Collaboration analysis of 43 exercise and weight-loss-related studies found that exercise helped people lose an average of two pounds. Whereas a “high” intensity exercise regimen lost people three pounds – without adapting diet at all. Data from the National Weight Control Registry shows that people who successfully keep pounds lost during dieting tend to exercise for 45 to 60 minutes a day. The fact is that exercise increases your metabolism, which burns more calories than inactivity. An intense workout can cause your metabolism to stay in high gear for hours afterward.

Myth #3: Exercise makes you hungrier

Not true, says David Stensel, Ph.D., a researcher at Loughborough University in England. In a study he conducted in 2010, subjects who exercised for 90 minutes on certain days, ate about the same amount of calories on workout days and sedentary days – there was no increased hunger. In fact, there is evidence that vigorous exercise can actually suppress appetite by depressing levels of the hunger-stimulating hormone ghrelin.

On the other hand, when your body senses a depletion of its energy sources (fat tissue, for example) it will respond with certain defensive measures. The level at which hunger feelings are increased due to exercise will vary based on a person’s genetics and individual chemical makeup.

It’s hard to find an excuse to stop participating in healthy exercise. The solution to this ongoing question is not to stop exercising, but to eat healthier foods.