Does Exercise Make You Hungry?

April Daniels Hussar,SELF magazine

Ever felt ravenous after aworkout? We've been there. But a new study reveals that this isn't necessarily the only response -- in fact, the fitter you get, the less likely you are to crave food after exercise.

The study, published last month in the Journal of Applied Psychology, divided 30 young, fit volunteers into two groups. One group strenuously exercised on stationary bikes for an hour, the other group just sat quietly. The groups switched activities for a second session. Immediately afterward, both groups were shown pictures of different kinds of foods, from healthy salads to sugary treats, while MRIs scanned their brains for activity in the food-reward regions.

Surprisingly (at least to those of us who are ravenous after a workout!) it was the sitters' brains that lit up at the sight of juicy cheeseburgers and ice-cream sundaes, while the exercisers' did not; in fact, none of the food elicited much of a response at all for those coming off the vigorous workouts.

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"The key takeaway here is that exercise suppresses food intake," Todd A. Hagobian, a professor of kinesiology at California Polytechnic who oversaw the study, tells HealthySELF, explaining that exercise affects the regions of your brain that control your desire to eat. Though Hagopian had hypothesized that exercise would decrease activity in food reward brain regions, he was surprised by the robustness of the effect of exercise on lowering brain activity.

A major significance of this study and others like it, says Hagobian, is that they illustrate how your desire for food intake is more affected by your brain than by your hormones. "A lot of the data, including some of ours, suggest that exercise does not impact hormones that regulate food intake, but exercise does suppress subsequent food intake," he says.

However -- if you're wondering why YOU always feel hungry after a workout, keep in mind that other factors are at play. "Those factors include visual food cues, learned behaviors, social context, cognitive state, availability of food, etc.," says Hagobian. "The brain integrates all these signals and determines whether to alter food intake."

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Also, it's not insignificant that the study participants were all in their 20s and fit enough to be able to vigorously ride a bike for a full hour. "Most studies showing that exercise decreases food intake have used fit people, whereas overweight/obese or sedentary people may not have the same magnitude of response," says Hagopian.

In other words, it's possible that the more in-shape you are, the less working out will make you want to eat -- and vice versa. In general, fitness levels have a major impact on a lot of biological aspects, explains Hagopian. "Fit people have a lower risk for chronic disease and fit people tend to weigh less than non-fit people," he says. "So if the brain determines whether to alter food intake, and exercise suppresses subsequent food intake mainly in fit people, it makes sense that fit people who exercise would have decreased activity in food-reward brain regions."

However, even if you become ravenous after a workout and end up taking in more extra calories than you've burned in the first place, there is hope!

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When it comes to getting yourself to the level of fitness where working out no longer makes you want to chow down on the entire contents of your pantry, Hagopian says, "People are different, and may respond to different doses of exercise." He recommends both trying different modes of exercise (running, swimming, aerobics, weight lifting, walking, tennis, etc.) and varying your amounts of exercise (higher intensity, longer duration) to determine the best combination for appetite control -- keeping in mind that higher intensity exercise is probably better at suppressing food intake and controlling appetite than lower intensity exercise. ("This is not to say that lower intensity exercise is not beneficial, but that higher intensity exercise has a more robust response in appetite regulation and suppressing food intake," Hagopian points out.)

If you are becoming fit and getting into shape, it's very probable that you will eventually experience lower hunger than when you first started exercising, says Hagobian. "This is a good thing, and may help 'curb' your appetite," he explains.


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