When people were put on a food restriction, scientists found that they had increased levels of the hunger hormone ghrelin and lower levels of the hunger-fighting hormone peptide YY. They also ate almost a third more at a buffet meal than people who exercised more.
On average, people who exercised more ate 660 calories at the buffet meal vs. the 944 calories eaten by people who simply ate less before the meal.
As a result, researchers concluded that exercise is more effective thanrestricting your diet if your goal is to cut back on calorie consumption—as most people looking to lose weight do.
“Some researchers have claimed that women’s appetites, appetite hormones, and food intake are more likely to increase after exercise than men’s—our new study shows that this is not the case, at least over the course of a single day,” says lead study author David Stensel, Ph.D., an associate dean in Loughborough University’s School of Sport, Exercise, and Health Sciences.
Stensel says he thinks many people are surprised that exercise does not necessarily increase food intake (at least in the short term), adding that he was too when he first started researching this topic.
So…what’s going on here?
While certified dietitian-nutritionist Gina Keatley acknowledges that the study was small, she calls the research “sound” and says there’s a valuable lesson here. “Drastically reducing calories is not the answer for weight loss,” she says. Amen, sister.
Aerobic exercise, like running, causes the body to repress the release of gherlin, or hunger hormones, says Keatley. When you compare that to just cutting back on your calorie intake and not having the hormone-repressing benefit of exercise, it just makes sense that you’d be hungrier when you didn’t eat as much.
Stensel says his study doesn’t necessarily confirm that exercise is better than diet for weight loss—just that you’ll probably be less hungry after working out than cutting way back on how many calories you ate.
And you can totally use this info to your advantage. If you’re trying to lose weight, it might be worth working out before you have breakfast or after work before dinner. You’ll likely end up eating less, which can really add up over time.
But, when it comes to the old diet vs. exercise debate, Stensel says you shouldn’t have to choose: “We think that both diet and exercise are important for weight loss in the longer term.”