Exercise and Appetite: Work Out and Eat Less?
According to a 2008 study, vigorous exercise reduces appetite in men. Researchers followed 11 young, healthy men after they ran for an hour on a treadmill. The men were allowed to rest for 7 hours and the session was repeated 2 more times. After each running session, the men were surveyed about their level of hunger and key appetite hormones were measured.
How did the treadmill run affect their appetite? Not only did a running workout suppress the appetite of these young men, but it also lowered levels of ghrelin, a hormone that increases the desire to eat. Ghrelin is produced by cells in the lining of the stomach and pancreas. It sends a message to the brain that energy stores are low, and it’s time to eat. The running session also boosted levels of peptide YY, a hormone produced by the intestines that suppresses appetite.
In this study, a vigorous aerobic exercise session transiently decreased levels of the appetite hormone ghrelin, increased levels of appetite-suppressing peptide YY and reduced the desire to eat. Does resistance exercise have the same effect?
Resistance Exercise and Appetite
In the same study, researchers had men do 90 minutes of strength training using weights and then allowed them to rest for 6 ½ hours. Again, they measured their levels of the appetite hormones ghrelin and peptide YY and surveyed them about their level of hunger. After weight-lifting, the men were still less hungry and levels of ghrelin were lower, but their peptide YY levels didn’t change. This suggests that vigorous aerobic exercise may be more effective than weight-training for suppressing appetite.
Exercise Suppresses Appetite another Way
Another study showed that aerobic exercise boosted levels of a blood protein called brain-derived neuropathic factor or BDNF. This protein helps to stimulate the growth of new nerve cells in the brain. It also may play a role in reducing appetite. In this study, higher levels of BDNF were linked with reduced food consumption. One more way exercise reduces appetite.
Can Exercise Help You Eat Less?
Even though exercise suppresses appetite transiently, that doesn’t necessarily mean you’ll eat less over a 24-hour period. Exercise may reduce appetite for short periods of time, but there could be a rebound effect later after the body completely recovers from an exercise session. You probably know people who gained weight after starting to exercise. Some people compensate for the calories they burn by eating more. Some studies also show that exercise suppresses appetite in men more than it does in women, so there are still unanswered questions about how exercise affects appetite.
One way to see how exercise affects your own appetite is to keep a food diary. After an exercise session, rate your level of hunger between 1 and 5 at various times throughout the day. When you take a day off from exercise, rate your appetite levels and compare. Keep track of how much you eat to see if you eat less on days you work out. A food diary is also a good way to make sure you’re not giving yourself too many “splurges” as a reward for exercising.
References:
AJP Regulatory Integrative and Comparative Physiology. 2008. “The Influence of Resistance and Aerobic Exercise on Hunger, Circulating Levels of Acylated Ghrelin and Peptide YY in Healthy Males”
Science Daily. “Aerobic Exercise Increases a Blood Protein That May Suppress Appetite”
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