健康：BMIにもとづく肥満診断の枠を超えて

Revising the way obesity is diagnosed, by combining additional metrics with traditional BMI measurements, increases obesity detection by between 3.3% and 7.4% compared with BMI-based classification, a paper in Nature reports. The study evaluates a new framework for diagnosing obesity, which was proposed in 2025, in 844,108 adults from China, the UK, the USA, and Spain. More accurate identification and definition of obesity cases could improve patient outcomes.

Over one billion people worldwide are affected by obesity. Despite this high prevalence, a lack of a clear clinical definition of the disease state has contributed to missed opportunities for care and prevention. Obesity has been traditionally assessed using BMI — a proxy for body size; however, BMI does not account for different body compositions or distribution of body fat, which can influence health risks. In 2025, the Lancet Diabetes & Endocrinology Commission proposed a new diagnostic framework that moves beyond BMI alone to incorporate body fat distribution and organ function and distinguishes clinical from pre-clinical obesity.

Using data from 844,108 adults from 4 large cohorts in China, the UK, the USA, and Spain, An Pan, Francesco Rubino, and colleagues show that this framework improves obesity classification compared with conventional BMI-based definitions. They found that BMI alone overestimated obesity in 1.2–3.1% of the participants and underestimated it in 5.2–8.6% of participants across the different study groups compared to the new framework. The authors note the value in distinguishing clinical obesity and preclinical obesity, which are shown to be distinct states with different patient outcomes. Clinical obesity was associated with substantially higher risk of death than preclinical obesity and only 10–30% of individuals with preclinical obesity progressed to clinical obesity over a period of 10 years. This finding indicates that the two health states would need different treatment approaches.

This study demonstrates the value in including more physical measures of body weight, composition, and fat distribution in obesity assessments, as well as organ function to identify different prognoses, which could help to guide patient care and inform health policy, the authors conclude.

• Article
• Open access
• Published: 11 November 2026
   
• Pan, A., Yang, S., Ramos, R. et al. Validation of clinical and preclinical obesity across global cohorts. Nature (2026). https://doi.org/10.1038/s41586-026-11237-5

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