Bone mass is positively influenced by lean and negatively by fat mass in overweight and obese postmenopausal women

Abstract

While it is well established that higher weight is associated with higher bone mass, it is under debate wether fat or lean mass has greater influence on bone mineral density/bone mineral content (BMD/BMC). Our purpose was to examine the influence of fat and lean mass on BMD/BMC of various skeletal sites in overweight and obese early‐postmenopausal Caucasian women. Subjects were classified according to their BMI as either overweight (BMI=25‐29 kg/m², n=74), or obese (BMI>30 kg/m², n=84). BMD/BMC of the total body (yielding body composition analysis), femur, spine and forearm were measured with iDXA. T‐test was used to compare differences between 2 groups. Multiple regression models with BMD/BMC of various skeletal sites as dependent variables, controlled for age and height (latter only in BMC models) were used to determine the influence of fat and/or lean mass. Obese women had significantly higher BMD/BMC in almost all skeletal sites than overweight women (p<0.05). In regression analysis, lean mass was significant positive predictor of total body BMD/BMC and spine BMC in both groups of women. Fat mass was negatively related to BMD/BMC of almost all skeletal sites but reached negative statistical significance for total body BMC in obese women. Our study shows that lean mass has positive, while fat mass might have negative influence on total body and regional BMD/BMC in this population. USDA/CSREES/NRI #2004‐05287.