Metabolic and Bariatric Surgery for Class I Obesity (Body Mass Index 30-34.9 kg/m2): A Comprehensive Literature Review.

Abstract

Class I obesity (body mass index [BMI]: 30-34.9 kg/m²) constitutes a considerable portion of the global obesity burden; however, traditional guidelines for metabolic bariatric surgery (MBS) have historically excluded this population. Recent updates in clinical consensus have expanded surgical eligibility, particularly for patients with obesity-related comorbidities refractory to medical treatment. To synthesize evidence from clinical studies, international guidelines, and expert consensus to assess the efficacy, safety, and long-term outcomes of MBS in patients with class I obesity. A comprehensive literature review was conducted, incorporating major clinical trials, observational cohorts, and meta-analyses published between 2006 and 2024. Weight loss, metabolic outcomes, and major surgical complication rates were examined. Recent studies demonstrate that MBS in patients with class I obesity achieves a total weight loss of 15.8-33.7%, and excess weight loss up to 102.7%, with type 2 diabetes mellitus remission rates frequently exceeding 60%. Complication rates remain low and are comparable to those observed in cohorts with higher BMI. Indirect comparisons suggest that the metabolic benefits and safety profiles in class I obesity are comparable to those in patients with higher BMI. Updated guidelines from international bariatric societies support MBS in class I obesity. MBS is an effective and safe treatment for weight loss and remission of comorbidities in class I obesity. Supported by recent guidelines and expert consensus, it should be considered as a valid treatment option for appropriately selected patients, with the potential to reduce their long-term healthcare burden.