The impact of the Lancet Commission definition of obesity on its prevalence and implications on long-term cardiovascular-kidney-metabolic outcomes in East Asians: Observational study of two community-based cohorts

Background The Lancet Commission proposed an update in January 2025 on the definition of obesity which requires at least one anthropometric measurement in addition to body mass index (BMI) to confirm excess adiposity. Also, the presence of obesity-related organ dysfunction is used to differentiate between clinical and pre-clinical obesity. We evaluated how applying the Lancet Commission proposed definition of obesity, which required an additional anthropometric measurement to verify excess adiposity, would affect its prevalence, and its implications on the cardiovascular-kidney-metabolic health. Methods and findings We used two representative Chinese community-based cohorts and compared five categories of participants with (i) clinical obesity, (ii) preclinical obesity, (iii) BMI ≥25 kg/m 2 without confirmed excess adiposity, (iv) overweight and (v) normal/underweight in the cross-sectional cohort for cardiometabolic risk profiles and in the longitudinal cohort for long-term cardiovascular-kidney-metabolic outcomes. In the cross-sectional cohort, the prevalence of obesity was 44.5% in men and 26.7% in women defined by the Asian BMI cutoff of ≥25.0 kg/m 2 , and decreased to 33.8% and 24.1%, respectively, using the Lancet Commission criteria (BMI ≥ 25.0 kg/m 2 and elevated waist circumference). Applying the Lancet Commission criteria would reclassify a portion of individuals who are initially classified as having obesity based on BMI criteria alone (BMI ≥ 25.0 kg/m 2 ) but with normal waist circumference to be non-obese (category iii). The individuals falling into category iii had an adverse cardiometabolic health profile which was intermediate among the five categories regarding insulin resistance and visceral adiposity (falling between categories ii and iv). In the longitudinal cohort with a median follow-up of over 20 years, people with clinical obesity had the poorest cardiovascular-kidney-metabolic outcomes including all-cause mortality, whereas those reclassified as non-obese had an intermediate risk of adverse cardiovascular-kidney-metabolic outcomes among the five categories. The main limitation of the study was that all participants were Chinese and findings might not apply to other ethnic groups. Conclusion Adoption of the Lancet Commission criteria would classify a small proportion of individuals with BMI of ≥25.0 kg/m 2 as non-obese. People with clinical obesity identified by the revised criteria had the highest risks of cardiovascular-kidney-metabolic outcomes including all-cause mortality, whereas individuals reclassified as non-obese had intermediate risks of cardiovascular-kidney-metabolic outcomes between those in pre-clinical obesity and overweight categories.