Association Between Obesity and Bone Mineral Density in Middle-Aged Adults

Background: The relationship between obesity and bone mineral density (BMD) varies in different studies. Our aim in this study was to explore the association between obesity (Body mass index ≥ 30) and BMD among adults 40-59 years of age. Methods This study was conducted on a sample of 2218 participants (986 men and 1232 women) aged from 40 to 59 years, from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. The independent variable was Body mass index (BMI) and the dependent variable was lumbar BMD. We performed weighted multivariate linear regression models and smooth curve fittings to evaluate the associations between BMI and lumbar BMD. Results The BMI was positively associated with lumbar BMD, after adjusting for other covariates (β 0.006; 95% confidence interval (CI) 0.003-0.008). An inverted U-shaped association between the BMI and lumbar BMD was further identified, with the point of infection was at about 50 kg/m 2 . On subgroup analyses, the relationship between BMI and lumbar BMD of women and blacks were inverted U-shaped. Conclusion Based on the result, it may be beneficial to appropriately increase BMI to promote BMD. However, considering the inverted U-shaped association, an excessive BMI may be harmful to bone health on women and blacks.