After two years, people who undergo metabolic and bariatric surgery achieve weight loss that is about five times greater than with non-surgical approaches.
Semaglutide and tirzepatide have become some of the most talked-about medications in modern weight loss care. Semaglutide is the active ingredient in Ozempic, a drug originally used for type 2 diabetes that is also widely known for helping people lose weight.
Tirzepatide is a newer injectable medication in the same broader class of metabolic drugs and has drawn attention for its effects on appetite and blood sugar. Both are taken as weekly injections and are part of a group called GLP-1 receptor agonists.
Even with all the buzz, a new head-to-head real-world study suggests these medications may not deliver weight loss on the same scale as bariatric surgery over the long term. Researchers reported that sleeve gastrectomy and gastric bypass were associated with about five-times more weight loss than weekly injections of the GLP-1 receptor agonists semaglutide or tirzepatide, at the end of two years. The findings were recently presented at the American Society for Metabolic and Bariatric Surgery (ASMBS) 2025 Annual Scientific Meeting.
Weight Loss Outcomes After Two Years
The analysis, led by researchers at NYU Langone Health and NYC Health + Hospitals, found a major gap between the two approaches. After two years, patients who underwent one of the bariatric procedures lost an average of 58 pounds. By comparison, patients who received a GLP-1 prescription for at least six months lost an average of 12 pounds (24% total weight loss vs. 4.7%).
Staying on the medication longer appeared to help, but it still did not close the gap. Patients on continuous GLP-1 therapy for a full year lost more weight than those treated for at least six months, yet their results remained far below those seen in surgery patients (7% total weight loss).
Real-World Outcomes Versus Clinical Trials
“Clinical trials show weight loss between 15% to 21% 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. We know as many as 70% of patients may discontinue treatment within one year,” said lead study author Avery Brown, MD, a surgical resident at NYU Langone Health. “GLP-1 patients may need to adjust their expectations, adhere more closely to treatment or opt for metabolic and bariatric surgery to achieve desired results.”
The researchers conducted a retrospective comparative effectiveness analysis using real-world electronic medical records from NYU Langone Health and NYC Health + Hospitals. The study included patients with a body mass index (BMI) of at least 35 who either underwent bariatric surgery (sleeve gastrectomy or Roux en-Y gastric bypass) or were prescribed injectable semaglutide or tirzepatide between 2018 and 2024.
To ensure a fair comparison, the team adjusted for differences in age, BMI, and comorbidities using average treatment effect weighting. They then evaluated outcomes across a total of 51,085 patients treated with either GLP-1 medications or surgical procedures.
Future Directions and Treatment Optimization
“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,” said study senior author and bariatric surgeon Karan R. Chhabra, MD, MSc, Assistant Professor of Surgery and Population Health, NYU Grossman School of Medicine.
About 12% of Americans say they have ever taken a GLP-1 drug, including 6% who say they are currently in treatment. A recent study found that more than half of patients with overweight or obesity (53.6%) discontinued GLP-1 therapy within one year (53.6%), a number that grows to 72.2% by two years. Meanwhile, utilization of metabolic and bariatric surgery remains exceedingly low. According to the ASMBS, more than 270,000 metabolic and bariatric procedures were performed in 2023, which represents only about 1% of those who meet eligibility requirements based on BMI.
Expert Perspective on Weight-Loss Treatments
“While both patient groups lose weight, metabolic and bariatric surgery is much more effective and durable,” said ASMBS President Ann M. Rogers, MD, FACS, FASMBS, who was not involved in the study. “Those who get insufficient weight loss with GLP-1s or have challenges complying with treatment due to side effects or costs, should consider bariatric surgery as an option or even in combination.”
According to the U.S. Centers for Disease Control and Prevention (CDC), the prevalence of obesity and severe obesity is 40.3% and 9.4%, respectively. Studies show the disease can weaken or impair the body’s immune system and cause chronic inflammation and increase the risk of scores of other diseases and conditions including cardiovascular disease, stroke, type 2 diabetes, and certain cancers.
Meeting: American Society for Metabolic and Bariatric Surgery (ASMBS) 2025 Annual Scientific Meeting
The study was supported by NYU CTSA grant KL2 TR001446 from the National Center for Advancing Translational Sciences at the National Institutes of Health (NIH).
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1 Comment
Its absolutely mind blowing we live in a world where we call poison “medication”.
Most modern drugs are no longer medication. They are poisons with horrifying side effects, consequences, and trade offs.
To “treat” one thing you often put yourself at risk of several (or even dozens) of other things.
These ads on TV regularly list “death” as a possible side effect on some of these poisons.
Shocking and sad.