ABSTRACT:Twenty‐four adult men were assigned to an experimental weight‐training group (N=10), or to an experimental jogging group (N=8), or to an active control group (N=6). Height, weight, skinfold thickness (ten sites), girth (four sites), and total body potassium (4 0K) were assessed before and after the exercise programs. After eight weeks of training, the weight‐training group had gained significantly more weight than the jogging group had lost, the jogging and weight‐training groups had lost significantly more fat than the control group, and the weight‐training group showed an increase in fat‐free weight which was significantly different from the changes in fat‐free weight for the other two groups. There were no differences between the three groups for any of the skinfold or girth measurements. Thus adults, given a constant diet, can favorably alter their fat‐free weight and fat weight by participating in regular physical exercise, under adequate medi