Bone Mineral Density Changes during Weight Regain following Weight Loss with and without Exercise

The purpose of this study was to compare changes in bone mineral density (BMD) over a 6 month follow up (period of weight regain) in overweight, postmenopausal women having previously completed a 6 month weight loss (WL) intervention with and without aerobic exercise (AEX). Women (BMI > 25 kg/m2) underwent VO2max and DEXA scans at baseline, after 6 months of WL or AEX + WL, and at 12 months ad libitum follow up. Both groups lost ~9% body weight from 0 to 6 months and regained ~2% from 6 to 12 months, while losing ~4% of appendicular lean mass (ALM) across the 12-month study duration. VO2max increased 10% from 0 to 6 months and declined 12% from 6 to 12 months for AEX + WL, with no changes for WL. Total body (p < 0.01) and total femur (p = 0.03) BMD decreased similar between groups across time (combined groups: 0–6 months: total body: −1.2% and total femur: −1.2%; 6–12 months: total body: −0.26% and total femur: −0.09%). Less ALM loss and greater VO2max increases during the WL phase were associated with attenuated BMD loss at various anatomical sites during periods of weight regain (6–12 months) p’s < 0.05). Results suggest that BMD loss may continue following WL, despite weight regain. Further, this study adds to the literature by suggesting that preventing declines in muscle quality and function during WL may attenuate the loss of BMD during weight regain. Future studies are needed to identify mechanisms underlying WL-induced bone loss so that effective practices can be designed to minimize the loss of BMD during WL and weight maintenance in older women.