TUESDAY, July 1, 2025 (HealthDay News) — For young adults, body fat percentage is a better predictor of 15-year mortality risk than body mass index (BMI), according to a study published online June 24 in the Annals of Family Medicine.

Arch G. Mainous III, Ph.D., from the University of Florida in Gainesville, and colleagues examined BMI versus body fat percentage for 15-year mortality risk among adults aged 20 to 49 years in a nationally representative cohort of U.S. adults in the National Health and Nutrition Examination Survey.

The researchers found that body fat percentage and waist circumference were significantly associated with 15-year, all-cause mortality (unadjusted hazard ratios, 2.01 and 1.94, respectively; adjusted hazard ratios, 1.78 and 1.59, respectively) and heart disease mortality (unadjusted hazard ratios, 4.20 and 4.75, respectively; adjusted hazard ratios, 3.62 and 4.01, respectively). No statistically significant association was seen for BMI with all-cause mortality. There was a significant association for BMI with heart disease mortality in the unadjusted model, but not in the adjusted model.

“The medical community has been aware that BMI has some limitations as a measure of body composition and disease risk. It is an indirect measure of body fat percentage,” coauthor Frank A. Orlando, M.D., from the University of Florida, said in a statement. “Direct measures have historically been too expensive and difficult to use in the office. Our study shows that a direct measure of body fat that can be done easily, practically and inexpensively in a doctor’s office solves the problems of BMI.”

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