Effects of exercise on appetite control: implications for energy balance.

At a time of increased obesity, decreased physical activity, and high food consumption, the relationship between physical activity and appetite control needs to be examined. Many people believe that the energy expended as a result of physical activity generates a drive to eat. However, a counterintuitive conclusion arises since there is no compelling evidence that increased physical activity increases energy intake. A suppression of hunger occurs following intense exercise; however, this effect is brief and has no influence on energy intake. Indeed, there does not appear to be any within-day effect of exercise on energy intake. Day-to-day effects of exercise on energy intake could occur, but only a few provocative data exist showing a delayed effect of exercise on energy intake 2 d later. Therefore, there appears to be only a weak short-term coupling between energy expenditure and energy intake. What about the effects of increased physical activity on food selection? The natural hypothesis would be that the energy reserves used during exercise would estimate a drive for a particular nutrient. There is no clear consistent evidence to indicate that in the short-term, exercise induces changes in food or nutrient preferences. In the long-term there is some evidence that physical activity is associated with an increase in carbohydrate intake, but it is uncertain whether these changes are biologically driven for a result of changes of a psychological nature. Contrary to a popularly held view, food selection and nutrient intake constitute patterns of behavior held in place by environmental contingencies and short-acting post-ingestive physiological responses; these patterns of behavior are relatively immune to modulation by the metabolic effects of exercise.