Overview
- Researchers published a Nature validation of the Lancet Commission framework using data from 844,108 adults, and the study showed the new definition outperforms BMI alone at identifying people with higher risk of death.
- The framework adds waist-based measures (waist circumference, waist-to-hip and waist-to-height ratios) with ethnicity-specific cutoffs to BMI so body-fat distribution is captured more accurately.
- On Nov. 11, 2026, study authors reported that the new criteria both overestimated obesity in up to 3.1% of people and underestimated it in up to 8.6%, producing a net rise in prevalence of up to 7.4% versus BMI alone.
- The proposal separates preclinical obesity (excess body fat without organ or functional impairment) from clinical obesity (excess fat plus at least one of 18 organ or functional impairments), and clinical obesity carried about a 69% higher all-cause mortality risk.
- Implementing the new definition would alter who is eligible for care and drugs, require clinician training on waist measures, and demand consensus and scoring for the 18 dysfunction criteria before it can be adopted in routine practice.