Two-Year Weight Loss With GLP-1 Medications Compared With Sleeve Gastrectomy in Adults With Obesity

This observational study will compare weight loss over two years in adults receiving GLP-1 receptor agonist medications with weight loss in adults who previously underwent laparoscopic sleeve gastrectomy, an operation that reduces the size of the stomach. Adults starting GLP-1 medications as part of their usual care will be followed for 24 months. Their results will be compared with existing medical records of adults who underwent sleeve gastrectomy at the same center. Treatment decisions will be made by patients and their treating clinicians as part of routine care, rather than assigned by the study. The main outcome is the percentage of starting body weight lost at 24 months. The study will also assess weight changes at earlier visits, medication side effects, treatment continuation and reasons for stopping treatment, and changes in weight-related health conditions. The groups will be matched using baseline characteristics to make the comparison more balanced.

Inclusion Criteria: GLP-1 Receptor Agonist Cohort: * Age 18 years or older at treatment initiation. * Initiation of a GLP-1 receptor agonist for obesity or overweight as part of routine clinical care. * Available baseline height and body weight measurements. * Willingness to attend at least one follow-up assessment. * Ability to comply with the center's standard follow-up program. * Provision of written informed consent. Laparoscopic Sleeve Gastrectomy Cohort: * Age 18 years or older at surgery. * Primary laparoscopic sleeve gastrectomy for obesity performed at the study center between January 1, 2020, and January 1, 2026. * Available preoperative height, body weight, and body mass index measurements. * Available demographic and baseline clinical data. * At least one documented postoperative body weight measurement. Availability of a 24-month weight measurement is preferred for the primary comparison. Exclusion Criteria: Both Cohorts: * Bariatric or metabolic surgery before the index treatment. * Revisional bariatric surgery as the index treatment. * Active malignancy or a serious systemic disease substantially affecting body weight. * Pregnancy or breastfeeding at the index treatment. * Uncontrolled endocrine disease that may cause weight loss. * Missing baseline height or body weight measurements. * Recent participation in another intensive weight-loss program before the index treatment. * Concurrent use of another anti-obesity treatment that could substantially affect study outcomes. * Inability to reliably verify study data. GLP-1 Receptor Agonist Cohort: * Short-term GLP-1 receptor agonist use for an indication other than weight management. * Medication prescribed but never administered. Laparoscopic Sleeve Gastrectomy Cohort: * Sleeve gastrectomy performed concurrently with another bariatric procedure. * Sleeve gastrectomy performed for an indication other than primary obesity treatment.