Overview
- An international study led by King’s College London tested the Lancet Commission’s two-step definition using records for 844,108 adults and found the new approach worked better than BMI at identifying people at higher risk of death, based on data published on November 11, 2026.
- The framework first confirms excess body fat with waist-based measures such as waist circumference or waist-to-height ratio and then classifies people as clinical obesity if at least one of 18 obesity-related organ or functional impairments is present and as preclinical obesity if no such impairments are found.
- Compared with BMI alone, the combined criteria underestimated obesity in up to 8.6% of people and overestimated it in up to 3.1%, raising measured obesity prevalence by roughly 3.3%–7.4% depending on the population.
- Health outcomes diverged by category: clinical obesity carried about a 69% higher all-cause mortality risk, preclinical obesity carried about a 19% increase, and between 77% and 91% of people with preclinical obesity did not develop clinical obesity over ten years.
- Routine adoption faces practical hurdles, including agreement on ethnic cutoffs, standardizing waist measurements, clinician training, and careful assessment of how reclassification would affect access to treatments, resource needs, and public‑health policy.