Relative contribution of weight‐bearing and non‐weight‐bearing effect of adipose tissue to bone mineral density in postmenopausal women

Abstract

To investigate the relative contributions of weight-bearing and non-weight-bearing effects of adipose tissue to bone mineral density (BMD) in postmenopausal women. The subjects were 228 postmenopausal women aged 50-75 years. Age, years since menopause (YSM), height, body weight, and body mass index were recorded. Trunk fat mass, body fat mass, bilateral leg BMD and lean (muscle) mass were measured by whole body scanning with dual-energy X-ray absorptiometry. The relationships of BMD to trunk and body fat mass were investigated using uni- and multivariable analyses. The amount of trunk fat mass and body fat mass were 8.7 ± 3.6 kg and 19.0 ± 5.9 kg, respectively. On Pearson's correlation test, right leg BMD was positively correlated with trunk fat mass (r=0.268, P<0.001) and body fat mass (0.299, P<0.001). On multiple linear regression analysis, trunk fat mass (t-value = 3.500, P<0.001), age (-2.431, P<0.05), and YSM (-2.564, P<0.01) were independent significant predictors of right leg BMD. However, body fat mass was not a predictor of BMD (-0.465, P=0.642). These relationships remained significant after further adjusting for right leg muscle mass. Trunk fat mass rather than body fat mass is a significant predictor of leg BMD at the most weight-bearing site, despite being less than half the amount of body fat mass. Thus, adipose tissue contributes more to BMD through non-weight-bearing effect rather than weight-bearing effect.