A study of 844,108 adults shows obesity diagnosis needs more than BMI

A Nature study analysed 844,108 adults across cohorts in China, the UK, the US and Spain, combining BMI with waist circumference and waist-to-height ratio while separating clinical obesity with organ dysfunction from preclinical obesity without it. BMI alone overclassified 1.2% to 3.1% and missed 5.2% to 8.6% across cohorts. Clinical obesity carried an all-cause mortality hazard ratio of 1.69 and preclinical obesity 1.19, while BMI-only obesity without the combined criteria did not show the same risk pattern. The results support multi-measure stratification, but this is observational cohort validation rather than personal diagnosis or treatment advice; cutoffs, population differences and causal attribution still require clinical judgment.