Non-weight-bearing effect of trunk and peripheral fat mass on bone mineral density in pre- and post-menopausal women.

Objective: To investigate the non-weight-bearing effect of trunk fat mass (composed of visceral and subcutaneous fat mass) and peripheral fat mass (subcutaneous fat mass alone) on bone mineral density (BMD) in pre- and post-menopausal women.

Methods: The subjects were 412 pre-menopausal women, 20-50 years of age and 228 post-menopausal women, 50-75 years of age. Age, years since menopause (YSM), height, body weight, and body mass index were recorded. Trunk, peripheral (extremities), left arm (non-weight-bearing site), lean mass, and BMD were measured by dual-energy X-ray absorptiometry.

Results: In pre-menopausal women, the amount of trunk fat mass was 6.8+/-4.1 kg, which was significantly lower than the amount of peripheral fat mass (11.6+/-3.8 kg, p < 0.001). Although trunk fat mass was positively correlated with arm BMD on Pearson's correlation test, arm lean mass was the only significant predictor of BMD on multiple regression analysis. In post-menopausal women, the amount of trunk fat mass (8.7+/-3.6 kg) was also significantly lower than the peripheral fat mass (10.3+/-3.4 kg, p < 0.001). On multiple regression analysis, however, trunk fat mass, but not arm lean mass, was the significant predictor of BMD. In both groups, peripheral fat mass was not correlated with left arm BMD.

Conclusion: The effect of adipocyte-derived biochemical factors on BMD may differ with menopausal status and the sites of adipocyte deposition.