Lawrence Berkeley National Laboratory

Objective: To determine if exercise reduces body weight and to examine the dose-response relationships between changes in exercise and changes in total and regional adiposity. Methods and Results: Questionnaires on weekly running distance and adiposity from a large prospective study of 3,973 men and 1,444 women who quit running (detraining), 270 men and 146 women who started running (training) and 420 men and 153 women who remained sedentary during 7.4 years of follow-up. There were significant inverse relationships between change in the amount of vigorous exercise (km/wk run) and changes in weight and BMI in men (slope+-SE:-0.039+-0.005 kg and -0.012+-0.002 kg/m2 per km/wk, respectively) and older women (-0.060+-0.018 kg and -0.022+-0.007 kg/m2 per km/wk) who quit running, and in initially sedentary men (-0.098+-0.017 kg and -0.032+-0.005 kg/m2 per km/wk) and women (-0.062+-0.023 kg and -0.021+-0.008 kg/m2 per km/wk) who started running. Changes in waist circumference were also inversely related to changes in running distance in men who quit (-0.026+-0.005 cm per km/wk) or started running (-0.078+-0.017 cm per km/wk). Conclusions. The initiation and cessation of vigorous exercise decrease and increase body weight and intra-abdominal fat, respectively, and these changes are proportional to the change in exercise dose.