A new real-world study highlights that metabolic and bariatric surgery remains the most effective long-term weight-loss intervention, outperforming popular GLP-1 medications such as semaglutide and tirzepatide by a significant margin.
Researchers found that patients who underwent bariatric procedures—including sleeve gastrectomy and gastric bypass—lost about five times more weight than those using weekly injections of GLP-1 receptor agonists over a two-year period. The findings were recently presented at the American Society for Metabolic and Bariatric Surgery (ASMBS) 2025 Annual Scientific Meeting.
Bariatric Surgery vs. GLP-1 Medications
Bariatric surgery works by reducing stomach size and altering gut hormones that regulate hunger and fullness. These changes help patients consume less food, feel satisfied sooner, and achieve long-lasting weight loss while also improving conditions such as type 2 diabetes and cardiovascular disease.
In the study led by NYU Langone Health and NYC Health + Hospitals, surgery patients lost an average of 58 pounds after two years. In contrast, those prescribed GLP-1 medications for at least six months lost an average of just 12 pounds—equivalent to 24% total weight loss for surgery patients versus 4.7% for medication users. Patients who continued GLP-1 therapy for a full year fared slightly better, with an average 7% total weight loss, but still fell far short of surgical outcomes.
Real-World vs. Clinical Trial Results
“Clinical trials report 15% to 21% weight loss for GLP-1s, but our real-world data suggest outcomes are considerably lower, even for patients maintaining prescriptions for an entire year,” said Dr. Avery Brown, lead study author and surgical resident at NYU Langone Health. “Many patients discontinue therapy within a year, underscoring the importance of managing expectations and considering surgical options for substantial results.”
The retrospective analysis included 51,085 patients with a BMI of 35 or higher who either underwent bariatric surgery or received injectable semaglutide or tirzepatide between 2018 and 2024. Researchers adjusted for age, BMI, and comorbidities to ensure a fair comparison.
GLP-1 Medications Explained
Semaglutide and tirzepatide act on the glucagon-like peptide-1 (GLP-1) pathway, which helps regulate appetite and blood sugar. Semaglutide directly mimics GLP-1, while tirzepatide targets both GLP-1 and a second hormone pathway to reduce hunger and improve glucose control. Both are administered via weekly injections.
Future Directions
Dr. Karan R. Chhabra, senior study author and bariatric surgeon at NYU Grossman School of Medicine, said future research will focus on optimizing GLP-1 outcomes, identifying which patients are better suited for surgery, and assessing the role of treatment costs in long-term success.
Despite rising popularity, GLP-1 medications have high discontinuation rates. More than half of patients stop therapy within a year, rising to 72.2% by two years, while bariatric surgery remains underutilized—only 1% of eligible Americans undergo procedures annually, according to ASMBS.
Expert Insight
“Both groups experience weight loss, but metabolic and bariatric surgery is far more effective and durable,” said ASMBS President Dr. Ann M. Rogers. “Patients struggling with GLP-1s or facing side effects or costs should consider surgery, potentially in combination with medication.”
The study underscores the persistent obesity epidemic in the U.S., where 40.3% of adults have obesity and 9.4% have severe obesity, conditions linked to chronic inflammation, weakened immunity, and elevated risk of heart disease, stroke, type 2 diabetes, and certain cancers.
The research was supported by NYU CTSA grant KL2 TR001446 from the National Center for Advancing Translational Sciences at the National Institutes of Health.
