Body Fat and Cardiometabolic Disease Burden and All-Cause Mortality in Adults With Normal Body Mass Index

To test the hypothesis that body adiposity measured by dual x-ray absorptiometry is associated with metabolic disorders and all-cause mortality in normal-weight individuals.

Adults 20 to 65 years of age with normal body mass index (BMI) and dual x-ray absorptiometry examination in the US National Health and Nutrition Examination Survey from 1999-2006 and 2011-2018 were evaluated. Follow-up was until December 2019. Weighted logistic regression and Cox proportional hazard models were performed to test the association between body fat percentage (BF%) and metabolic disorders (ie, insulin resistance, metabolic syndrome, dyslipidemia, type 2 diabetes mellitus, and hypertension) and mortality. Models were adjusted for potential confounders while considering complex survey design and were further stratified by sex and BF% as tertiles in normal-weight individuals.

Included in this study sample were 20,613 individuals of whom 6424 were normal weight by BMI (18.5-24.9 kg/m²) (45.7% men, 69.6% non-Hispanic Whites). Every 10-unit percent increase in total BF% was associated with a higher risk for insulin resistance, metabolic syndrome, dyslipidemia, and all-cause mortality in the normal BMI group. Metabolic disorders were associated with BF% tertiles.

Even in these normal weight subjects, increases in body adiposity are significantly associated with increased cardiometabolic disease burden and mortality.