Body composition and bone mineral density in premenopausal and postmenopausal obese women

Abstract

Background Bone mineral density (BMD) is strongly linked to body weight. Overweight exerts mechanical stress on the bone and prevents aging-induced decrease in BMD. Despite the positive association between BMI and BMD and bone mineral content (BMC), the role of fat distribution in BMD remains unclear. The aim of our study is to examine the relation between body composition and regional BMD in premenopausal and postmenopausal obese Egyptian women. Materials and methods This cross-sectional study included 50 obese Egyptian women with a mean age of 52.9±10.9 years and BMI over 30. They were divided into a premenopausal group (n=21) and a postmenopausal group (n=29). Total and regional BMD and body composition were measured by dual-energy X-ray absorptiometry (Lunar). BMD was measured at the hip, lumbar spine, and total body (BMD and BMC). Anthropometric measurements were performed for all participants. Results The premenopausal group had significantly higher total body BMD, BMC, and femur BMD than the postmenopausal group, whereas postmenopausal women had a significantly higher waist to hip ratio and trunk to total fat mass (FM) ratio than premenopausal women. The results of the multiple-regression analysis stepwise method showed that spine BMD, femur BMD, and whole-body BMD had significant correlations with the total lean mass (LM) and the trunk to total FM ratio in the postmenopausal women, whereas the total BMD was significantly correlated with the total LM only in the premenopausal women. Conclusion It can be concluded that lean body mass is a significant determinant of BMD in premenopausal obese women, whereas both body lean and fat mass are significant determinants of regional and total BMD in postmenopausal obese women. The study suggests that LM and FM have an alternative impact on BMD in premenopausal and postmenopausal Egyptian obese women.