Ann Fam Med

Body fat percentage outperforms BMI for mortality prediction in young adults

June 27, 2025

Study details: This nationally representative cohort study analyzed U.S. adults aged 20 to 49 years from the National Health and Nutrition Examination Survey, examining the predictive value of BMI, body fat percentage (BF%), and waist circumference (WC) for 15-year all-cause and heart disease mortality using Cox proportional hazards models. Standard BMI categories and established BF% and WC thresholds were applied.

Results: BF% and WC were both significantly associated with increased 15-year all-cause and heart disease mortality (adjusted hazard ratio for BF% and all-cause mortality, 1.78; 95% confidence interval [CI], 1.28–2.47; for WC, 1.59; 95% CI, 1.12–2.26). BMI, in contrast, showed no statistically significant association with all-cause mortality after adjustment, and its association with heart disease mortality wasn't significant in adjusted models.

Clinical impact: The findings suggest that BF% is a superior predictor of long-term mortality risk in adults aged 20 to 49 years compared with BMI. Incorporating BF% into clinical risk assessment may improve identification of at-risk individuals in this age group and could prompt a shift away from exclusive reliance on BMI for body composition evaluation and mortality risk stratification.

Source:

Mainous AG, et al. (2025, June 24). Ann Fam Med. Body Mass Index vs Body Fat Percentage as a Predictor of Mortality in Adults Aged 20-49 Years. https://pubmed.ncbi.nlm.nih.gov/40555527/