Does working out make you eat more?

by Mary C. Weaver, CSCS on September 17, 2012

Woman wearing electrodes looks at pictures of food

Getting your sweat on early in the day may be one of the best ways to prevent overeating later on.

Yes, I know some of you are convinced that exercising boosts your appetite—and if you’re starving yourself while dieting, that could happen.

But assuming that’s not the case, some cool new research indicates that working out in the morning could actually make it easier to moderate impulsive eating behavior (you know—like going overboard on pizza or ice cream) throughout the day.

Here’s a summary of the findings. On one day 35 women—about half of whom were normal-weight and the other half obese—spent 45 minutes in the morning walking briskly on a treadmill. On a control day, one week later, the women did no exercise.

Then, while wearing an electrode-studded headpiece, the women looked at images of food and flowers. The flowers were just there as controls. What counted was how study participants’ brains fired when looking at delicious dishes.

The idea was to measure their brain activity and responses to the food images to see whether having spent those 45 minutes exercising had any effect on those responses.

In the words of one of the scientists, Michael Larson, “Our main finding was that on the exercise day, they had diminished response or attentional response to those pictures of food, so the brain responded less, so you can see why they had less motivation for the food.”

Well, that’s all very nice, but what does it mean for you? The study also measured the women’s food intake, and participants did not eat more calories on the workout day. On both days, they ate more or less equal amounts.

And since their exercise did not stimulate a desire to eat, they ended up getting the calorie-burning effects of the workout.

Huge caveat here: I know oodles of women who allow themselves to eat more when they’ve exercised, because, as they tell me, they figure they’ve burned a ton of calories and can accommodate whatever treats come their way.

The logical flaw here is that most women vastly overestimate the number of calories burned through exercise and underestimate the number of calories in that gooey cheese- or chocolate-covered yummy.

(Here’s a good source of info on calories burned through exercise.)

And just FYI, a 150-pound person walking at 3.8 miles per hour (the average pace used in the study) would burn about 250 calories during that 45-minute workout.

The bottom line: morning exercise can be a powerful weapon in your weight-loss arsenal. So if you burn 150, 200, 300, or more calories through your workout and don’t eat more than usual, you win.

Photo: A BYU student wears an EEG recording device to demonstrate how researchers measured neural responses to food after exercise. Photographer Mark A. Philbrick. Source: Brigham Young University


Google Analytics Alternative