Metabolic and bariatric surgery in mild obesity: mid-term outcomes and safety in an Asian population

Background Metabolic and bariatric surgery (MBS) is an established treatment for severe obesity, but its role in Asian patients with mild obesity (body mass index BMI 27.5-32.5 kg/m²) remains controversial due to limited mid-term evidence. This study evaluated the ≥3-year outcomes of MBS in this population compared with patients with BMI ≥32.5 kg/m². Objective To evaluate the mid-term (≥3 years) efficacy and safety of MBS in Asian patients with mild obesity, compared with those with BMI ≥MIhe kg/m². Methods In this retrospective cohort study, 26 patients with mild obesity and 76 matched patients with higher BMI underwent MBS between 2013 and 2020. Outcomes included percent total weight loss (%TWL), metabolic control, remission of obesity-related comorbidities, and postoperative complications. The primary composite endpoint was defined as glycated hemoglobin 6.5%, low-density lipoprotein cholesterol 2.6 mmol/L, systolic blood pressure 130 mmHg, and homeostasis model assessment of insulin resistance 2.5 mmol/L, μU/mL. Results At a mean follow-up of approximately 5 years, the mild obesity group achieved lower %TWL than the higher-BMI group (approximately 20% vs 26%, P 0.05). Despite this, the rate of achieving the composite metabolic endpoint was comparable (30.7% vs 27.6%, P = 0.76). Both groups demonstrated sustained improvements in glycemic control, lipid profile, blood pressure, and insulin resistance. Remission of type 2 diabetes, hypertension, hyperuricemia, and metabolic-associated fatty liver disease increased significantly in both groups (all P 0.05). Notably, a substantially greater proportion of patients in the obesity group achieved normalization of body weight (BMI 24 kg/m²). Complication rates were low and comparable. Conclusion In Asian patients, MBS appears safe and provides durable metabolic benefits across BMI categories. Despite losing less weight, those with mild obesity achieved similar cardiometabolic improvements and were more likely to reach a normal BMI. These findings are preliminary. Future research should prioritize large, multicenter studies focusing on the BMI 27.5–30 kg/m² subgroup without advanced metabolic disease, randomized trials comparing surgery with current pharmacotherapies, and long-term studies tracking hard cardiovascular endpoints.