Bariatric surgery outpaces GLP-1 weight-loss drugs in two-year study, NYU finds

Bariatric surgery produced far greater weight loss than injectable GLP-1 medications over two years in a New York University Langone Health analysis, spanning more than 14,000 patients who either used the drugs for at least six months or underwent surgery. On average, surgery patients shed about 58 pounds, compared with 12 pounds for those taking semaglutide or tirzepatide, a gap of roughly 46 pounds.

To compare the groups fairly, researchers used propensity score matching to pair each medication patient with a similar surgery patient. The study began with more than 140,000 patients treated between 2018 and 2024—122,595 on GLP-1 medications and 18,136 who had weight-loss surgery—and ended with about 14,000 matched pairs after balancing factors such as age, starting weight and blood sugar.

Lead author Dr. Avery Brown, a surgical resident at NYU Langone Health, said that while clinical trials show weight loss of roughly 15% to 21% with GLP-1 drugs, real-world results appear much lower, even among patients with ongoing prescriptions for a year. The two-year real-world analysis found surgery patients lost about 26% of their total body weight, versus about 5% for those on injectable medications, a fivefold difference.

In a separate, ideal-use analysis focusing on the 146 matched pairs where patients adhered to their treatment plans for two full years, the gap narrowed but remained substantial: medication patients lost about 8% of body weight, while surgery patients lost about 25%. The team also found that surgery more consistently improved long-term blood sugar control over the two-year period, an outcome particularly important for patients who are obese and have diabetes.

The researchers note that GLP-1 drugs, which mimic hormones that curb appetite, carry a spectrum of side effects from mild nausea to more disruptive gastrointestinal changes. They also come with ongoing costs, and adherence can be a challenge, with as many as 70% of GLP-1 users stopping their prescriptions for a variety of reasons, including side effects or price.

Dr. Ann M. Rogers, president of the American Society for Metabolic and Bariatric Surgery, which funded the research, said: “While both patient groups lose weight, metabolic and bariatric surgery is much more effective and durable. 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.”

Surgery works by physically altering the stomach and gut to limit intake and hormonal signals, while GLP-1 medications work by suppressing appetite signals in the brain. The two primary bariatric procedures examined in broader research are sleeve gastrectomy and Roux-en-Y gastric bypass.

A sleeve gastrectomy removes about 80 percent of the stomach, transforming it into a narrow sleeve that restricts food intake and reduces hunger hormones, supporting significant and lasting weight loss. Gastric bypass creates a small stomach pouch and reroutes a portion of the small intestine, combining reduced intake with altered absorption of calories and nutrients. Both approaches are associated with substantial weight loss, but Roux-en-Y and sleeve procedures differ in their mechanisms and long-term risk profiles.

The NYU Langone study adds to a growing body of evidence comparing surgical and pharmacologic obesity treatments. Earlier work, including a 2024 Pennsylvania-based study, tracked health records of more than 30,000 obese patients who were either prescribed injectable drugs or underwent bariatric surgery; after roughly two years, surgery patients lost about 28% of body weight, compared with 10% for those on medications. Another 2024 analysis involving roughly 20,000 patients across New York, Germany and Austria found that one year after surgery, patients lost about 30% of their body weight and maintained about 25% of that loss for up to ten years, while weight loss from injections plateaued at roughly 22.5% for tirzepatide and 10–15% for semaglutide, with stopping medication associated with about half the weight regained within a year.

Although bariatric surgery requires a higher upfront cost and a more intensive recovery, proponents argue it offers a one-time intervention that changes physiology in ways that support durable weight loss and broader health benefits, potentially reducing long-term medical expenses compared with chronic drug therapy that requires ongoing, lifetime payments. The NYU Langone analysis underscores the durability of surgical results and highlights the real-world gap between optimal clinical trial outcomes for GLP-1 medications and their everyday performance.

The study’s authors note that the patient populations in the medication and surgery groups had different baseline health profiles—namely higher obesity and COPD rates among GLP-1 users—which the team attempted to control for with propensity score matching. While no observational study can fully eliminate all confounding, the matching approach helps create a fairer comparison by aligning key factors such as weight, age and metabolic health.

For patients weighing options, the researchers say the choice between a drug-based approach and surgery should consider not only potential weight loss but also the durability of results, the likelihood of adherence, cost considerations, potential side effects, and the patient’s overall health profile. In particular, physicians and patients should discuss whether a staged approach—using GLP-1 therapy to achieve initial weight loss and then pursuing metabolic surgery for long-term maintenance—might be appropriate on a case-by-case basis.

The NYU Langone study is part of a broader push to understand how best to treat obesity, a condition linked to elevated risk for diabetes, cardiovascular disease and other health problems. It also contributes to ongoing policy discussions about access to bariatric surgery and coverage decisions by insurers and public health programs. As researchers continue to analyze longer-term outcomes, the findings suggest that, for many patients, surgery may offer a more reliable route to substantial and sustained weight loss than injections that require lifelong, ongoing use.