Donald Lamkin, University of California Los Angeles – The Debate on Exercise for Weight Loss

If you want to lose weight, hit the gym, right?

Donald Lamkin, assistant professor of psychiatry & biobehavioral sciences at the University of California Los Angeles, explores why it might not be that simple.

Donald M. Lamkin, Ph.D. is an Assistant Professor in the UCLA David Geffen School of Medicine and a Research Scientist at the Cousins Center for PNI in the UCLA Semel Institute for Neuroscience & Human Behavior. His research focuses on biobehavioral mechanisms in stress physiology, physical exercise, and cancer control.

The Debate on Exercise for Weight Loss

A recent debate among scientists highlights the growing notion that the exercise part of “diet and exercise” may not help you maintain a healthy weight. 

At the center of this debate is a theory called the “Constrained Total Energy Expenditure Hypothesis,” which asserts that exercise won’t help you burn more calories overall and, thus, won’t help you lose weight. 

Obesity researchers take issue with this, because the hypothesis is not based on randomized controlled trials, or RCTs, the gold-standard of scientific evidence.  And many RCTs do, in fact, show that supervised exercise regimens cause weight loss.

But do all RCTs show this effect? Commentators on the debate pointed to a review of more than a hundred RCTs on exercise and weight loss.  The review found that exercise can have a modest effect on weight loss, but it fails to prevent weight from coming back after dieting.

And this is not necessarily because you sometimes fail to adhere to your exercise routine or because you’re burning too few calories when you do exercise.

Instead, it may be that your body responds to regular exercise by decreasing the number of calories you burn when you’re not exercising.  That’s according to the constrained energy hypothesis.

Researchers recently tested this possibility by measuring non-exercise calorie burn in adults, both before and after a 6-month-long exercise program. Participants who exercised at a dose designed to facilitate weight loss, indeed, had a decrease in their metabolic rate by the study’s end.

So maybe both sides of the debate are right.  Exercise might help you take off a few unwanted pounds. But, as others have noted, you can’t “outrun a bad diet” by simply exercising more.