Does Exercise Really Make You Fat?

Uncovering the Facts vs. Fiction About What Role Exercise Plays in Weight Loss

Is it true that exercise can make us fatter?

By Bill Campbell, Ph.D., Exercise and Performance Nutrition Laboratory, University of South Florida

You likely have heard about the Time Magazine article "Why Exercise Won't Make You Thin" by John Cloud that was published in August of this year. This article had the effect of throwing a large rock into an angry bee's nest, causing exercise physiologists and personal trainers everywhere to get their John Cloud voodoo doll and insert pins from all angles. A close inspection of Cloud's article follows, in which I will justify some of his conclusions and question others with the aid of my background in human physiology.

In the article, Cloud states (and this is the main point of the article): "…while it's true that exercise burns calories and that you must burn calories to lose weight, exercise has another effect: it can stimulate hunger. That causes us to eat more, which in turn can negate the weight-loss benefits we just accrued. Exercise, in other words, isn't necessarily helping us lose weight. It may even be making us fatter"¹. In support of his article, Cloud cites several scientific studies^2-4.

Support of the Article

On the one hand, this hypothesis is correct. If one ingests more calories than they expend, they will gain weight. There is no argument to that—unless you deny the first law of thermodynamics (in which case you probably also question the law of gravity and the roundness of the earth). The real question is does exercise really stimulate hunger leading to overeating? There is not a simple answer to this, with some studies indicating that it does and other studies indicating that it does not^4,5.

Since science does not provide a conclusive answer to this question, we must resort to something that is agreed upon by all scientists and those who are physically active—the simplistic art of discipline.

If we want to lose weight, we must discipline ourselves to exercise and monitor our food intake. For those of you reading this article, this is likely your lifestyle—one of discipline at the dinner table and discipline in your training program.

Criticisms of the Article

Cloud came to his conclusions based on overweight subjects who focused on aerobic type exercise, like running on a treadmill.

Upon closer inspection of Cloud's article, two things stand out. First, in the studies that Cloud cited to justify his point, overweight subjects were used (not individuals who are currently active). In this overweight population, exercising alone (without monitoring caloric intake) would likely not result in drastic reductions in bodyfat.

If you have ever been overweight, you know how hard it truly is to lose excess bodyweight. Science has demonstrated repeatedly that those who are successful in this endeavor consistently exercise and monitor their food intake⁶. It's not enough to do just one or the other.

The second thing that stands out when putting this article under the microscope is that in each of the studies that Cloud states, the mode of exercise was aerobic (primarily consisting of treadmill running and stationary cycling)². Therefore, any conclusions made were not in consideration of resistance training.

Resistance training has been shown repeatedly to increase skeletal muscle tissue, which is approximately three times more metabolically active than fat tissue. Further, resistance training is the best mode of exercise to change one's physique. In fact, in one recent study in which resistance training was utilized as the mode of exercise, it was shown that the hunger response following the training bout did not lead to overconsumption of food⁵. This finding contradicts one of Cloud's basic premises of his article—that exercise stimulates hunger, which can lead to overeating.

Conclusion

"Cloud's article... completely ignores one of the primary modes of exercise that improves metabolism and physique improvements—resistance training."

Cloud's article states the obvious—overeating leads to gaining bodyweight, primarily in the form of bodyfat. The assumption that exercise can lead to overeating is speculative at best and completely ignores one of the primary modes of exercise that improves metabolism and physique improvements—resistance training.

As I stated before, those of you reading Real Solutions likely already live a disciplined lifestyle, partake in resistance training, monitor your food intake, and take advantage of sports supplements that optimize your training adaptations.

Living this disciplined lifestyle is not easy. And remember, Rome wasn't built in a day. Transforming your body from an out-of-shape couch potato into a lean, healthy force (that is actually maintainable) really comes down to some basic nutritional and exercise knowledge (which you can learn about in every issue of Real Solutions) combined with good old-fashioned discipline.

References

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