Bariatric surgery far more effective than GLP-1 drugs for weight loss in NYU study

Bariatric surgery produced substantially greater weight loss over two years than injectable GLP-1 medications in a real-world analysis from New York University, with patients who underwent sleeve gastrectomy or gastric bypass losing an average 58 pounds over the period, compared with about 12 pounds for those taking GLP-1 drugs such as semaglutide (Ozempic, Wegovy) or tirzepatide (Zepbound). The findings, based on more than 14,000 matched pairs, point to a sizable 46-pound gap in total weight loss between the procedures and the medications.

Researchers compiled data from a large pool of more than 140,000 patients who either took GLP-1 medications for at least six months (122,595 people) or underwent weight-loss surgery (18,136 people) between 2018 and 2024. To ensure fair comparisons, scientists used propensity score matching, pairing each patient who took medications with a surgically treated counterpart sharing similar age, starting weight and blood-sugar profile, resulting in about 14,000 matched pairs. In the real-world analysis, surgery participants lost about 26 percent of their total body weight over two years, while medication users lost about five percent, yielding a fivefold advantage for surgery. Because many GLP-1 users discontinue treatment, the researchers also analyzed a subset in which patients remained on therapy for the full two-year period, noting that adherence varied widely.

In a separate, “perfect-use” analysis focusing on the 146 matched pairs in each group whose members adhered to their treatment for the full two years, the gap narrowed but remained in favor of surgery. Medication users who continued injections for the full two years lost about eight percent of their body weight, while surgery patients lost roughly 25 percent, indicating that even with optimal adherence, surgery tends to produce more substantial weight loss.

The study also found that surgery provided greater improvements in long-term blood sugar control over the two-year window, a particularly important outcome for patients who are obese and have diabetes. Dr. Avery Brown, a surgical resident at NYU Langone Health and the study’s lead author, noted that clinical trials of GLP-1 drugs report weight losses of 15 to 21 percent, but real-world results appear much more modest, especially as many patients stop taking prescriptions for various reasons such as side effects or cost. “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,” Brown said.

The study emphasizes that bariatric surgery is a one-time procedure that creates lasting physiological changes, whereas GLP-1 medications require ongoing monthly injections and can come with a range of side effects from mild nausea to disruptive changes in bathroom habits. Researchers also highlighted a stark disparity in utilization: about 280,000 weight-loss surgeries are performed annually in the United States compared with roughly 8.4 million GLP-1 prescriptions.

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

The two main bariatric procedures studied—sleeve gastrectomy and gastric bypass—achieve weight loss through complementary mechanisms. Sleeve gastrectomy removes about 80 percent of the stomach, creating a narrow tube that restricts food intake and suppresses hunger hormones. Gastric bypass forms a small stomach pouch and reroutes a portion of the small intestine, both restricting intake and reducing calories and nutrient absorption. Together, the procedures often yield substantial, durable weight loss: sleeve patients typically shed 50 to 70 percent of their excess body weight (and up to about 25 percent of total body weight in some cases), while gastric bypass patients commonly lose 60 to 80 percent of their excess body weight.

GLP-1 drugs work by mimicking a hormone that signals the brain to curb eating and reduce cravings, offering significant but generally smaller and less durable weight loss than surgery. The medications are associated with a broad range of effects and costs, including the need for ongoing treatment and potential discontinuation by some patients.

Context from other studies reinforces the NYU findings. A Pennsylvania-based analysis published in 2024 tracked more than 30,000 obese individuals enrolled in a state insurance plan and found surgery produced greater weight loss than prescriptions over roughly two years, with surgeons’ patients losing about 28 percent of body weight versus 10 percent for those on medications. In another large review from 2024 involving about 20,000 patients across New York, Germany and Austria, researchers reported an initial weight loss of roughly 30 percent within a year after surgery, with about 25 percent of that weight loss maintained for up to ten years. By comparison, maximum losses for tirzepatide hovered around 22.5 percent after 17 to 18 months and 10 to 15 percent for semaglutide, with many patients regaining about half of lost weight within a year after stopping the drugs.

Despite the higher upfront cost and longer recovery associated with surgery, analysts say the one-time procedure can be a more cost-effective, durable path to weight loss and related health improvements over a patient’s lifetime than ongoing medication regimens for Wegovy or similar drugs. The NYU researchers say further work is needed to help patients and clinicians weigh options and to determine how best to combine strategies for those who need more than one approach to achieve sustained weight loss.