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.

The prevalence of obesity decreased when applying the Lancet Commission definition compared to BMI-only criteria in both men and women.

• Using the Asian BMI cutoff of ≥25.0 kg/m2, obesity prevalence was 44.5% in men and 26.7% in women in the cross-sectional cohort.
• Using the Lancet Commission definition (BMI ≥25.0 kg/m2 and elevated waist circumference), prevalence decreased to 33.8% in men and 24.1% in women.
• The reduction was more pronounced in men (44.5% to 33.8%) than in women (26.7% to 24.1%).

Individuals reclassified as non-obese under the Lancet Commission definition (BMI ≥25.0 kg/m2 but normal waist circumference) had an intermediate adverse cardiometabolic health profile.

• This reclassified group (category iii) had cardiometabolic risk profiles intermediate among the five categories regarding insulin resistance and visceral adiposity.
• Their profile fell in between pre-clinical obesity (category ii) and overweight (category iv).
• This group was initially classified as obese by BMI criteria alone but had normal waist circumference.

In the longitudinal cohort with over 20 years of follow-up, clinical obesity was associated with the poorest cardiovascular-kidney-metabolic outcomes including all-cause mortality.

• The longitudinal cohort had a median follow-up of over 20 years.
• Outcomes assessed included cardiovascular-kidney-metabolic outcomes and all-cause mortality.
• People with clinical obesity had the poorest outcomes among all five categories examined.
• Individuals reclassified as non-obese had intermediate risk of adverse cardiovascular-kidney-metabolic outcomes among the five categories.

The Lancet Commission definition requires at least one anthropometric measurement in addition to BMI to confirm excess adiposity, and uses presence of obesity-related organ dysfunction to differentiate between clinical and pre-clinical obesity.

• The Lancet Commission proposed this updated definition in January 2025.
• Five categories were compared: (i) clinical obesity, (ii) preclinical obesity, (iii) BMI ≥25 kg/m2 without confirmed excess adiposity, (iv) overweight, and (v) normal/underweight.
• Two representative Chinese community-based cohorts were used: one cross-sectional and one longitudinal.
• All participants were Chinese, which the authors identified as the main limitation, as findings might not apply to other ethnic groups.

Individuals reclassified as non-obese under the Lancet Commission definition had intermediate long-term risks of adverse cardiovascular-kidney-metabolic outcomes between those in pre-clinical obesity and overweight categories.

• This intermediate risk positioning was consistent with their intermediate cardiometabolic risk profiles observed in the cross-sectional analysis.
• The reclassified individuals had worse outcomes than the overweight category but better outcomes than those with pre-clinical obesity.
• The finding suggests that reclassification to non-obese status does not indicate absence of cardiometabolic risk.