Uh oh. There may be trouble in energy balance land.
In the Stand Up and Eat blog we have touted the energy (i.e., calorie) burning benefits of all different types of movement. Getting people to burn more calories to balance out the calories they eat is a way to prevent weight gain. With the epidemic of obesity growing unabated, that’s a good thing.
But a recent study published in the American Journal of Clinical Nutrition shows that exercising may make it a bit harder to lose weight - for some people1. It turns out that getting active may affect appetite – for some people.
In a study conducted in Australia, researchers had 58 overweight men and women exercise to burn 500 calories a day, five days a week for 12 weeks. They exercised in a lab so the scientists could be certain that they burned the right number of calories each session. Participants also completed questionnaires about hunger and appetite throughout the study.
At the end of the 12 weeks, 32 of the subjects (responders) lost a significant amount of weight. But strangely enough, the other 26 (nonresponders) lost only a small amount of weight. As it turns out, the nonresponders increased their daily calorie intake whereas the responders did not. Why?
Analysis of the hunger and appetite data suggest that exercise caused an increase in nonresponders’ hunger levels. This probably contributed to them eating more during the study and ultimately, their lower weight loss compared to the responders.
While we have not been wrong to promote physical activity as a way to combat overweight and obesity, this study points out that people respond to exercise differently. And right now, scientists don’t know how to determine for whom exercising might increase appetite. So keep the following in mind:
1 King NA et al. Dual-process action of exercise on appetite control: increase in orexigenic drive but improvement in meal-induced satiety. American Journal of Clinical Nutrition. 2009;90:921-927.