November 11, 2026

New clinical definition versus BMI in diagnosing obesity

In 2025, the Lancet Diabetes & Endocrinology Commission proposed a new diagnostic framework for obesity that went beyond BMI alone to incorporate other metrics such as body fat distribution and organ function, and which distinguished between clinical and pre-clinical obesity.

Some of the same researchers have now carried out a study to test whether this framework outperforms BMI in identifying differences in health conditions and mortality risk.

The new study was published in Nature and looked at data from 844,108 adults from four large cohorts from the UK, Spain, China and the USA. It investigates the value of including more physical measures of body weight, composition, and fat distribution in obesity assessments to identify different prognoses, and whether this could help to guide patient care and inform health policy.

The study also estimates what proportion of obesity is ‘clinical obesity’ (an active disease) versus ‘preclinical obesity’.

Speakers included:

Prof Francesco Rubino, Chair of Metabolic and Bariatric Surgery, King’s College London; and senior author of the study

Prof An Pan, Professor of Epidemiology, Huazhong University of Science and Technology in Wuhan, China; and first author of the study