Aerobic exercise maintains regional bone mineral density during weight loss in postmenopausal women.

This study examines the effects of weight loss by caloric restriction (WL) and aerobic exercise plus weight loss (AEx+WL) on total and regional bone mineral density (BMD) in older women. Healthy, postmenopausal women [age 63 +/- 1 (SE) yr] not on hormone-replacement therapy underwent 6 mo of WL (n = 15) consisting of dietary counseling one time per week with a caloric deficit (250-350 kcal/day) or AEx+WL (n = 15) consisting of treadmill exercise three times per week in addition to the weight loss. Maximal aerobic capacity increased only in the AEx+WL group (P < 0. 001). Body weight, percent fat, and fat mass decreased similarly in both groups (P < 0.005), with no changes in fat-free mass. Total body BMD (by dual-energy X-ray absorptiometry) decreased in both groups (P < 0.05). Femoral neck, Ward's triangle, and greater trochanter BMD decreased in the WL group (P </= 0.05) but were not significantly different after AEx+WL. L2-L4 BMD did not significantly change in either group. Thus WL and AEx+WL both result in losses of total body BMD; however, AEx+WL appears to prevent the loss in regional BMD seen with WL alone in healthy, older women. This suggests that the addition of exercise to weight-loss programs may reduce the risk for bone loss.