Abstract
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 40 to 59 years from the National Health and Nutrition Examination Survey 2011-2018. The independent variable was body mass index (BMI). The outcome variable was lumbar BMD. The associations of BMI with lumbar BMD were examined using multivariable linear regression models. RESULTS: 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 BMI and lumbar BMD was further identified, with the point of infection at approximately 50 kg/m(2). In the subgroup analyses, the relationship between BMI and lumbar BMD in women and blacks was an inverted U-shape. CONCLUSION: Based on the results, it may be beneficial to appropriately increase BMI to promote BMD. However, considering the inverted U-shaped association, excessive BMI may be harmful to bone health in women and blacks.