5 Minutes
Study summary and headline findings
Researchers at New York University compared two common bariatric procedures—sleeve gastrectomy and Roux-en-Y gastric bypass—with outcomes for patients using GLP-1–based medications such as semaglutide (marketed as Ozempic for diabetes and Wegovy for weight loss) and tirzepatide. Using electronic health records, investigators matched patients on age, body mass index (BMI) and baseline blood glucose control to compare two-year weight-loss results in real-world clinical settings.
The primary finding was a substantial difference in average weight change: patients who underwent bariatric surgery lost a mean of 25.7% of total body weight over two years, while those treated with GLP-1 receptor agonists lost an average of 5.3% in the same interval. The gap persisted across shorter follow-up windows as well, with surgery consistently delivering the larger magnitude of sustained weight reduction.
Mechanisms, adherence and clinical context
GLP-1 receptor agonists such as semaglutide mimic the endogenous glucagon-like peptide-1 hormone, reducing appetite and slowing gastric emptying—physiological effects that support weight loss and improved glycemic control. Tirzepatide combines activity at GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors and has shown strong effects in clinical trials.
Bariatric procedures produce durable anatomic and metabolic changes: sleeve gastrectomy reduces stomach volume and alters gut hormone signaling, while gastric bypass reroutes food flow and amplifies hormonal shifts that suppress appetite and improve insulin sensitivity. These anatomical changes are permanent and help explain larger, sustained weight loss compared with pharmacotherapy.
Adherence to medication emerged as an important factor. The NYU team noted that, in practice, GLP-1 users frequently discontinue therapy—estimates cited in the study suggest up to 70% may stop within a year—reducing real-world effectiveness below the 15–21% weight-loss figures reported in controlled clinical trials. NYU surgical resident Avery Brown highlighted this gap: "Clinical trials show weight loss between 15 percent and 21 percent for GLP-1s, but this study suggests that weight loss in the real world is considerably lower even for patients who have active prescriptions for an entire year."
Safety, benefits and trade-offs
GLP-1 drugs retain important benefits: originally approved for type 2 diabetes, these medications lower blood glucose and have been associated with reductions in cardiovascular risk and some cancer-related outcomes in observational studies. In the NYU analysis, bariatric surgery also achieved superior blood-sugar control compared with medication alone.
However, surgery carries procedural risks and is invasive and permanent. Postoperative success still depends on long-term dietary and lifestyle changes, and not all candidates choose or are eligible for surgery. Conversely, GLP-1 therapy is less invasive, reversible, and has rapidly increased in use—prescriptions reportedly doubled between 2022 and 2023—which raises questions about cost, access, and long-term adherence.
The study acknowledged potential sources of bias: it was funded by the American Society for Metabolic and Bariatric Surgery (ASMBS), an organization that supports surgical interventions. The authors emphasize that the results do not dismiss GLP-1 therapies; rather, they call for clearer guidance on which patients are likely to achieve optimal outcomes with medication versus surgery.
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Future directions and research priorities
Lead investigators and clinicians framed next steps around personalization of care. Karan Chhabra, a bariatric surgeon at the NYU Grossman School of Medicine, said: "In future studies we will aim to identify what healthcare providers can do to optimize GLP-1 outcomes, identify which patients are better treated with bariatric surgery versus GLP-1s, and determine the role out-of-pocket costs play in treatment success." Future research priorities include randomized comparisons, longer follow-up, cost-effectiveness analyses and studies of adherence interventions.
Expert Insight
Dr. Elena Morales, a clinical endocrinologist and obesity researcher (fictional), comments: "The NYU data remind clinicians that pharmacologic efficacy in trials does not always translate to equivalent real-world results. When discussing options with patients, we must weigh the magnitude and durability of weight loss, comorbidity benefits such as improved glycemic control, patient preference, and long-term adherence barriers, including cost and side effects." This perspective underlines the need for individualized treatment planning using multidisciplinary teams.
Conclusion
The NYU comparison indicates that bariatric surgery produces substantially greater average weight loss than GLP-1 medications in routine clinical practice across two years of follow-up. GLP-1 drugs remain an important, less invasive option with metabolic benefits, but real-world adherence and cost issues limit their average effectiveness relative to surgery. Determining the right treatment for each patient requires further research into predictors of success, long-term outcomes, and the financial and behavioral supports needed to sustain therapy.
Source: mayoclinic
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