Body weight and menopausal status influence trabecular and cortical bone mineral density

A higher body weight has been shown to be protective against osteoporosis, while a low body weight is known to be associated with increased risk for fractures. The effects of obesity on bone quality are not clear, since there are reports suggesting that fracture risk in more obese individuals may be greater than expected. A review of how obesity may influence bone density and quality and fracture risk is discussed. Preliminary data is presented from our laboratory examining both obesity and menopause as independent factors on trabecular and cortical true volumetric bone mineral density (vBMD) using peripheral computerized tomography. We analyzed vBMD of the tibia in healthy women with a wide range of body weight (65–227 kg). We found that higher body mass index (BMI) may protect against trabecular bone loss after menopause, while cortical vBMD may be more sensitive to aging. We suggest that the tibia (a weight-bearing site) is sensitive to changes in body weight, and that aging and menopausal status have differential effects on vBMD. These results underscore the need to examine hormonal or nutritional regulators of bone quality as a goal for future studies, and could have important clinical implications for obese individuals who lose weight.