Surgical versus medical treatment of obesity in the New Era: A systematic review

Background: Obesity has entered a new therapeutic era. The clinical conversation is no longer restricted to lifestyle counseling followed by late referral for bariatric surgery; it now includes highly effective anti-obesity pharmacotherapy, especially glucagon-like peptide-1 receptor agonists and dual glucose-dependent insulinotropic polypeptide/glucagon-like peptide-1 receptor agonists. The central practical question for clinicians is no longer whether obesity should be treated aggressively, but which modality should be prioritized, for whom, and at what stage of disease.
Methods: This systematic review was structured according to PRISMA 2020 principles. A focused search of PubMed, Scopus, Web of Science, and the Cochrane Library identified contemporary evidence comparing metabolic/bariatric surgery and medical therapy for obesity. Landmark randomized trials, long-term cohort studies, and high-quality systematic reviews/meta-analyses were prioritized. Outcomes of interest included total body weight loss, glycemic control, diabetes remission, cardiovascular effects, durability of response, adverse events, and practical implications for treatment selection.
Results: Thirty studies were synthesized. Bariatric surgery remained the most reliable intervention for large and durable weight reduction and for diabetes remission, particularly Roux-en-Y gastric bypass and sleeve gastrectomy. Modern pharmacotherapy, however, substantially narrowed the historical efficacy gap. Liraglutide produced modest but clinically meaningful weight loss, semaglutide moved average outcomes into the mid-teen percentage range, and tirzepatide reached weight reductions exceeding 20% in some trials. Semaglutide also demonstrated cardiovascular event reduction in patients with obesity and established cardiovascular disease without diabetes. Yet drug withdrawal frequently led to clinically significant weight regain, whereas surgery generally produced greater durability, albeit with procedural risk and long-term nutritional surveillance requirements.
Conclusions: In the new era, the relationship between surgery and medical therapy should be viewed as complementary rather than adversarial. Surgery remains the reference standard for severe obesity, advanced metabolic disease, and patients needing the highest probability of durable remission. Modern pharmacotherapy has become a powerful first-line or bridging strategy for many patients, especially those with lower surgical readiness, lower BMI, or preference for nonoperative treatment. A patient-centered, phenotype-based, and longitudinal care model is more appropriate than a simplistic surgery-versus-medicine dichotomy.