A JAMA Network Open study published on October 19, 2026, reveals that 73.8% of 2,316 bariatric surgery candidates meet the Lancet Commission's new criteria for clinical obesity involving organ dysfunction. Despite similar body mass index levels across candidates, those with clinical obesity carry higher surgical risks and achieve slightly lower weight loss. Authors recommend using these criteria to prioritize surgery for high-need patients as obesity medications expand.
Prevalence across international study cohorts
- ▪Clinical obesity prevalence among metabolic bariatric surgery candidates varied across international centers, ranging from 62.7% in the Brazilian cohort to 79.3% in the United Kingdom cohort.
- ▪Investigators evaluated 2,316 adult gastric bypass and sleeve gastrectomy patients from centers in London, Barcelona, Lille, and São Paulo using the Lancet Diabetes & Endocrinology framework.
- ▪A JAMA Network Open study of 2,316 adults undergoing metabolic bariatric surgery between 2014 and 2025 found that 73.8% (1,709 patients) met criteria for clinical obesity.
Comparison of patient characteristics
- ▪Bariatric surgery candidates with clinical obesity were older than those with preclinical obesity across all study cohorts, averaging 45.6 to 48.9 years compared to 34.7 to 40.0 years.
- ▪Mean body mass index and distribution across BMI categories (<40, 40-49, and ≥50) did not differ significantly between clinical and preclinical obesity groups within surgical centers.
Surgical risks and post-operative outcomes
- ▪Bariatric surgery patients with clinical obesity lost modestly less weight post-surgery, trailing preclinical obesity patients by 2 to 4 percentage points in several study cohorts at 12 and 24 months.
- ▪Patients with clinical obesity experienced higher baseline American Society of Anesthesiologists surgical risk classifications across all four international study cohorts compared to preclinical obesity patients.
- ▪In the French cohort analyzed in the study, major 30-day post-operative complications occurred in 4.0% of clinical obesity patients compared to 1.1% of preclinical obesity patients.
Recommendations for surgical prioritization
- ▪Study authors suggested health systems with limited surgical capacity prioritize metabolic bariatric surgery for patients demonstrating clinical obesity-related organ dysfunction.
- ▪Study authors proposed bariatric surgery serve as a first-line treatment for clinical obesity, but as a second-line risk-reduction option for preclinical obesity as pharmacotherapy expands.
Economic considerations by obesity stage
- ▪Study authors noted bariatric surgery in clinical obesity may offer faster economic returns due to reduced post-operative complications, decreased medication use, and fewer hospitalizations.
- ▪Study authors stated bariatric surgery for preclinical obesity should be evaluated as a preventive intervention with longer time horizons and distinct cost-effectiveness thresholds.
Framework development and lead author
- ▪Dr. Francesco Rubino of King's College London, who led the commission, served as corresponding author for the JAMA Network Open study.
- ▪A Lancet Diabetes & Endocrinology Commission led by Dr. Francesco Rubino in January 2025 proposed separating clinical obesity from preclinical obesity based on organ dysfunction.
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