A new real-world study shows that bariatric surgery dramatically outperforms popular weight loss medications, including GLP-1 receptor agonists like semaglutide and tirzepatide, in achieving significant, lasting weight reduction.
The research, presented at the American Society for Metabolic and Bariatric Surgery (ASMBS) 2025 Annual Scientific Meeting, analyzed outcomes for over 51,000 patients treated between 2018 and 2024 across the NYU Langone Health and NYC Health + Hospitals systems.
Patients who underwent bariatric procedures—sleeve gastrectomy or Roux-en-Y gastric bypass—lost an average of 58 pounds over two years, equivalent to roughly 24% of total body weight. By comparison, patients using GLP-1 injections for at least six months lost an average of just 12 pounds, or 4.7% of body weight. Even those who remained on GLP-1 therapy continuously for a year saw only 7% weight loss, far below surgical results.
“Clinical trials suggest GLP-1 drugs can deliver 15% to 21% weight loss, but in real-world use, results are much lower,” said Dr. Avery Brown, lead author and surgical resident at NYU Langone Health. “Many patients discontinue treatment within the first year, which limits effectiveness. Patients may need to adjust expectations, adhere strictly to therapy, or consider bariatric surgery for more substantial outcomes.”
The study highlights the gap between controlled clinical trials and real-world usage, where side effects, costs, and adherence challenges often blunt the impact of medication-based therapies.
Researchers analyzed electronic health records for patients with a BMI of at least 35 who either received bariatric surgery or a GLP-1 prescription. Using statistical methods to adjust for age, BMI, and co-morbidities, the study compared outcomes for 51,085 patients. Funding came from an NYU CTSA grant supported by the National Institutes of Health.
Bariatric Surgery Underused Despite Proven Effectiveness
Despite its superior results, bariatric surgery remains underutilized. The ASMBS reports that over 270,000 procedures were performed in 2023—roughly 1% of those eligible based on BMI. GLP-1 drugs, meanwhile, are widely used, with 12% of Americans having tried them and 6% currently using them, but high dropout rates remain a challenge: 54% discontinue within one year, rising to 72% by two years.
“Metabolic and bariatric surgery is far more effective and durable,” said ASMBS President Dr. Ann M. Rogers, who was not involved in the study. “Patients struggling with weight loss on GLP-1 therapy or facing side effects or cost issues should consider surgery, or even a combination of treatments.”
Obesity Remains a Critical Public Health Concern
According to the U.S. Centers for Disease Control and Prevention, 40.3% of U.S. adults are obese, and 9.4% have severe obesity. Obesity increases the risk of chronic diseases, including cardiovascular disease, type 2 diabetes, stroke, certain cancers, and immune dysfunction.
The study’s authors emphasized the need for future research to identify which patients may benefit most from surgery versus medication, optimize GLP-1 therapy outcomes, and understand how out-of-pocket costs influence treatment success.
