Abstract
To explore the association between body mass index (BMI) and total lumbar bone mineral density (BMD) in adults. This study included 9927 participants from 2011 to 2020 National Health and Nutrition Examination Survey (NHANES). The date on BMI, total lumbar BMD and other covariates were collected. Multivariate linear regression analyses were performed to evaluate the association between BMI and total lumbar BMD. Smoothing curve fitting and saturation effects analysis models were used to analyze the nonlinear relationships and saturation values. Multivariate linear regression analyses revealed that BMI was positively linked to total lumbar BMD in non-adjusted models (β = 0.003, 95% CI: 0.003-0.003, P < .00001). After adjusting for gender and race (β = 0.003, 95% CI: 0.003-0.004, P < .00001) and all covariates (β = 0.004, 95% CI: 0.003-0.004, P < .00001), the association still existed. Smoothing curve fitting showed that there was nonlinear correlation between BMI and total lumbar BMD with saturation effect. The BMI saturation value was 21.2 kg/m2 in the total lumbar BMD based on saturation effects analysis models. There was nonlinear positive correlation between BMI and total lumbar BMD with saturation effect. For adults, keeping the BMI at a reasonable value (21.2 kg/m2) would obtain an optimal balance between BMI and total lumbar BMD.