Exercise Makes Me Hungry!
Many people think that exercise will make them hungrier, and that the calories they burn while exercising will be more than made up for by the extra food they'll eat. But most studies suggest that when people exercise moderately, they tend to eat only slightly more than when they don't work out.
Athletes in strenuous training do eat much more than usual, but they almost always burn the extra calories. Remember, however, that even if you don't lose weight when you start exercising regularly, you're likely to become trimmer and fitter, since you'll build muscle and lose some body fat.
During the first hour or so after a workout, appetite tends to drop, especially if you exercise strenuously. But over the longer term, energy expenditure and intake tend to be in balance.
It's hard to generalize, however, about this effect of exercise. Appetite regulation is a complex process, involving blood sugar levels, a variety of hormones and other chemicals, and psychological factors. Exercise's effect on appetite may also depend on whether you are overweight or not, a woman or man, previously sedentary or athletic, as well as the frequency, duration, and intensity of your workouts. Moreover, the effect is likely to be different once exercise becomes habitual, because of the body's adaptation processes during a long-term exercise regimen.
A balancing act
If you're trying to lose weight, or at least not gain weight, exercise is your friend. Studies comparing the roles of calorie reduction and exercise in weight loss have generally found that the greater benefit comes from dieting. But combining exercise and diet is usually best. Exercise not only burns calories, but also helps prevent the loss of muscle mass and the drop in metabolic rate that usually accompany dieting. And once you're at your desired weight, exercise is an excellent way to prevent or minimize future weight gain.
Source: Originally published in The University of California, Berkeley Wellness Letter (March 2011)