A big US study found that, for people with severe obesity, having bariatric surgery (like sleeve gastrectomy or gastric bypass) leads to about three times more weight loss than using GLP‑1 drugs such as tirzepatide, and it actually costs less over two years because the drug group keeps paying high pharmacy bills.

Obesity is a chronic condition with negative consequences for patients, the health care system, and society. The most effective treatment of class II and III obesity is metabolic bariatric surgery (MBS), which is usually considered a last resort. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have recently shown promising results. To compare weight loss and ongoing costs associated with MBS and GLP-1 RAs in the US. This cohort study used data from the Highmark Health insurance claims database and the Allegheny Health Network electronic medical record in the US. Participants were patients with class II or III obesity treated with either MBS or GLP-1 RAs who were enrolled in Highmark insurance for at least 6 months prior to index treatment and had follow-up data available for at least 12 months. Using propensity score weighting, the populations were adjusted for differences in baseline spending, health care utilization, age, sex, comorbidities, and smoking status. Data were analyzed from July 2024 to July 2025. MBS (sleeve gastrectomy or gastric bypass) vs GLP-1 RAs (dulaglutide, exenatide, liraglutide, lixisenatide, semaglutide, or tirzepatide). The main outcomes were total weight loss and monthly ongoing costs (pharmacy, medical, and surgery costs) at baseline and over 2 years after index treatment. Mean adjusted costs were calculated using a linear mixed-effects model. Analyses included 30 458 patients (mean [SD] age, 50 [11] years; 20 118 [66.1%] female), with 14 101 undergoing MBS (mean [SD] follow-up, 34 [16] months) and 16 357 receiving GLP-1 RAs (mean [SD] follow-up, 32 [17] months). After propensity score weighting, baseline characteristics were comparable. The mean (SE) total costs over 2 years were $63 483 ($1563) for GLP-1 RAs and $51 794 ($1724) for MBS (P < .001). The main driver of this difference was higher sustained pharmacy costs in the GLP-1 RA group throughout year 2 of follow-up. Comparing weight loss data of 257 patients using GLP-1 RAs and 1291 patients who underwent MBS, total weight loss was greater for the MBS group (mean [SE], 28.3% [0.3%]) than the GLP-1 RA group (mean [SE], 10.3% [0.5%]) (P < .001). These findings suggest that MBS was associated with more weight loss at lower ongoing costs compared with GLP-1 RAs in class II and III obesity. Further study is needed to determine if MBS should still be considered the last resort in treating obesity.