GLP-1 receptor agonist therapy before bariatric surgery: Effects on weight loss and body composition in clinical practice.

INTRODUCTION: The use of anti-obesity medications, particularly including glucagon-like peptide-1 receptor agonists (GLP1-RA), is expanding and increasingly combined with bariatric surgery (BS). However, evidence on their use preoperative and impact on body composition remains limited. PURPOSE: To compare weight loss and body composition changes in patients undergoing BS with or without prior GLP1-RA treatment. PATIENTS AND METHODS: Retrospective observational study of adults who underwent BS at Clínica Universidad de Navarra (Madrid) between 2017 and 2023. RESULTS: Overall, 86 patients (mean age, 46.6 ± 12 years; 66% women) were included; 80.2% and 19.8% underwent sleeve gastrectomy and gastric bypass, respectively. Preoperative GLP1-RA therapy (63.4% liraglutide and 36.6% semaglutide) was prescribed in 34.8% of patients for a mean of 21.7 ± 15.9 weeks. Adverse events were mild and mostly gastrointestinal symptoms. Patients treated with GLP1-RA achieved greater weight loss preoperatively (5.1% ± 4.9% vs. 2.4% ± 3.7%; p = 0.005) and at 1 month postoperatively (15.4% ± 5.2% vs. 13.0% ± 3.8%; p = 0.03), but not at 6 months. Prior to BS, fat mass was lower in the GLP1-RA group (53.3 kg [95% CI 50.7-56.0] vs. 58.6 kg [95% CI 56.6-60.5]; p = 0.01), whereas no differences in lean mass or body composition were observed at 6 months between the two groups. CONCLUSIONS: Preoperative GLP1-RA therapy resulted in greater preoperative weight and fat mass reduction without additional lean mass loss. Larger prospective studies are warranted to define the long-term role of GLP1-RA therapy before BS.