In order to understand how to curb appetite, an awareness of what triggers appetite in the brain is a good place to start. A study conducted at the University of Texas Southwestern Medical Center sought out to determine how exercise affects appetite and metabolism, specifically focusing on the melanocortin circuit.
The melanocortin circuit is a network in the brain's hypothalamus that directly influences metabolism. There are two types of neurons within the circuit, the neuropeptide Y (NPY) and the pro-opiomelanocortin (POMC). These neurons are designed to counteract each other. NPY cells make you want food, while POMC neurons curb appetite.
Mice have a melanocortin circuit similar to ours, so the researchers gave them an exercise routine. Picture the tiniest treadmill you have ever seen. Adult mice ran for 60 minutes at a vigorous pace, broken up into 20-minute segments. The control group was placed on a tiny, unmoving treadmill. Afterward, the mice were free to eat, or not eat, totally up to them. On a microscopic level, researchers also checked the neuronal activity in some of their brains by probing living cells. They repeated these tests numerous times over the course of 10 days.
Exercise significantly affected the melanocortin circuitry in the mice. The neurons that curb appetite (POMC) were much more active in the mice that ran, and stayed active for up to 48 hours after the workout. The NPY cells (the ones that increase appetite) were also quieter after exercise, though this effect only lasted about 6 hours. To corroborate these findings, the mice who worked out also ate less afterwards than they normally would. (The researchers had been studying these mice for a while.)
While it would be too bold to link exercise to curbed appetite in humans based on this study alone, these findings do suggest that it’s probably worth a try. For dieters, those of us looking to maintain a healthy weight or just stave off cravings-- it wouldn't hurt to start running.
Read more in The New York Times.