Effects of wheel running on food intake and weight gain of male and female rats.

Adult male and female rats were housed in a sedentary condition or given free access to a running wheel for 50 days. Running wheel activity of female rats was higher than that of males throughout the experiment. Food intake, of both male and female rats that could take exercise increased, and the rate of increase of females was greater than that of males. In both males and females there was a positive correlation between food intake and running wheel activity. These findings suggest that the sex difference in the rate of increase in food intake elicited by wheel running is at least partly explained by the sex difference in running wheel activity. Although food intake increased as a function of running wheel activity, the weight gains of both sexes were slower than those of sedentary rats. In both sexes this slower weight gain was mainly due to less accumulation of fat.