JAMA Netw Open

The new definition of obesity applies to 75% of U.S. adults

January 5, 2026

More than 75% of U.S. adults are considered obese, according to criteria that include 3 anthropometric factors (waist circumference, waist-to-hip ratio, waist-to-height ratio) specified in the Lancet Commission's obesity criteria. Based on the new criteria, more than a third of adults in this cross-sectional database study were reclassified as obese, compared with a BMI-only definition. Estimated obesity prevalence increased significantly with age—nearly every adult over age 50 was considered obese. Researchers suggest that age-specific criteria are warranted.

This cross-sectional study involved National Health and Nutrition Examination Survey (NHANES) data on 14,414 U.S. adults, from 2017 to 2023.

• Obesity prevalence was similar between men and women—and trended upward significantly with age. Prevalence was higher in Hispanic adults.
• All patients with BMI 30+ were classified as obese. Additionally, 80% of those with BMI 25 to <30—as well as 39% of those with BMI <25—also met new criteria for obesity.
• In adults with BMI 30+, waist-to-height ratio >0.50 was the most common abnormal anthropometric factor, seen in 80% of adults, followed by waist-to-hip ratio, which was elevated in 73%; elevated waist circumference was seen in 40%. Researchers applied alternative obesity definitions in Asian adults.
• The Lancet commission concluded that additional research was warranted regarding waist-to-height ratio. If a waist-to-height ratio cut-off of >0.60 were used, obesity prevalence in this study drops to 58%.

Source:

Al-Roub NM, et al. (2025, December 29). JAMA Netw Open. Body Mass Index and Anthropometric Criteria to Assess Obesity. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2843225