Association between body fat and bone mineral density in non-obese post-menopausal women over 60 years old

Background: Loss of bone mineral density is one of the most important complications of menopause. The results of studies about the relation between body fat and bone mineral density are controversial. The aim of this study was to determine the association between fat mass and bone mineral density on non-obese post-menopausal elderly women. Methods: This cross-sectional study is a part of the second phase of the Amirkola Health and Ageing Project (AHAP) that has been done on 356 elderly women with BMI of 18.5- 30. Bone mineral density (BMD) and total body fat were measured using the Hologic Horizon-WI densitometer. Statistical tests were ANOVA, Pearson’s correlation coefficient and multiple linear regression and a p- value less than 0.05 was considered significant. Results: The mean age of the participants was 70.22±7.34 and the mean age of menopause was 47.68±5.05. Women with highest fat mass had a greater spine, femur and whole-body BMD (p<0.0001). In this study, we observed a direct and positive significant correlation between body fat mass and BMD at spine (r=0.308), femur (r=0.420) and whole body (r=0.312) (p<0.0001). Adjusted linear regression showed positive effect of fat mass on BMD on all three anatomical sites especially in total femur (β=0.254, p<0.0001). Conclusion: This study showed a positive correlation between fat mass and bone mineral density at all sites in post-menopausal women.