Bone turnover and density in obese premenopausal women during moderate weight loss and calcium supplementation

Bone turnover is increased during weight loss in postmenopausal women and c an be suppressed with calcium supplementation. In this study, we assessed t he influence of energy restriction with and without calcium supplementation (1 g/day) in premenopausal women, Thirty-eight obese premenopausal women ( body mass index [BMI] of 35.0 +/- 3.9 kg/m(2)) completed a 6-month study of either moderate weight loss or weight maintenance. During weight loss, wom en were randomly assigned to either a calcium supplementation (n = 14) or p lacebo group (n = 14) and lost 7.5 +/- 2.5% of their body weight. The contr ol group of women (Iz 10) maintained their body weight. Total body and lumb ar bone mineral density (LBMD) and content were measured by dual-energy X-r ay absorptiometry (DXA) at baseline and after weight loss. Throughout the s tudy, blood and urine samples were collected to measure bone turnover marke rs and hormones. During moderate energy restriction, dietary calcium intake decreased (p < 0.05) and the bone resorption marker deoxypyridinoline (DPD ) increased slightly (p < 0.05) without evidence of bone loss. Calcium supp lementation during weight loss tended to increase lumbar BMD by 1.7% (p = 0 .05) compared with the placebo or weight maintenance groups. In contrast to our previous findings in postmenopausal women, premenopausal obese women w ho consume a low calcium diet do not lose bone over a 6-month period, wheth er their weight is stable or decreasing moderately.