Weight-loss-associated changes in bone mineral density and bone turnover after partial weight regain with or without aerobic exercise in obese women

BACKGROUND/OBJECTIVES:Moderate, long-term weight loss results in the loss of bone mass in overweight or obese premenopausal women. However, whether these changes persist during weight maintenance or regain remains to be determined.SUBJECTS/METHODS:Overweight or obese (body mass index: 25.8-42.5 kg/m ²) women (n=40) with at least two risk factors for the metabolic syndrome participated in this 12-month study that examined the effects of prescribed weight loss and regain, with or without exercise, on bone turnover and on bone mineral density (BMD) in a subset of participants (n=24). During the first 6 month, participants lost ∼10% of their initial body weight via energy restriction and supervised aerobic exercise. Following weight loss, participants were randomly assigned to either an exercise or a no exercise treatment for the regain (+50% of weight lost) phase. A one-way (time) repeated measures one-factor analysis of variance (RMANOVA) tested the effects of weight loss on BMD and bone turnover, and a two-way RMANOVA (time, exercise) was used to examine the effects of exercise during weight regain.RESULTS:Hip (P=0.007) and lumbar spine (P=0.05) BMD decreased with weight loss, and remained reduced after weight regain with or without exercise. Likewise, the weight-loss- associated increases in osteocalcin (P<0.001) and C-terminal peptide of type I collagen (P<0.001) persisted following weight regain, independent of exercise.CONCLUSIONS:The results of the present study, which is the first to examine changes in bone mass and turnover during carefully controlled weight regain, suggest that weight-loss-induced perturbations in bone mass and turnover persist after partial weight regain, regardless of whether regular weight-bearing aerobic exercise was continued.