People who begin obesity treatment with glucagon-like peptide-1 receptor agonists (GLP-1) and subsequently undergo metabolic/bariatric surgery can achieve significantly greater weight loss than with drug therapy alone, according to new research presented today at the American Society of Metabolic and Bariatric Surgery Annual Meeting (#ASMBS2026).
Researchers at New York University Grossman School of Medicine found that patients treated with GLP-1 drugs, either semaglutide or tirzepatide, lost about 8% of their total body weight in the months before surgery. Total weight loss increased to more than 25% in patients who later switched to gastric bypass surgery and to approximately 20% in patients who underwent sleeve gastrectomy. By comparison, patients who underwent direct surgery lost approximately 2% to 3% more weight after surgery, indicating that GLP-1 had little attenuated effect.
As more patients undergo surgery after GLP-1 therapy, it is important to understand how prior treatment affects outcomes. Our findings demonstrate that metabolic and bariatric surgery continues to result in significant and sustained weight loss in this population. ”
Karan R. Chhabra, MD, MS, senior study author, assistant professor of surgery and population health, New York University Grossman School of Medicine
The study analyzed the electronic health records of more than 6,700 patients who were prescribed GLP-1 drugs in the six months before surgery. Of these, 2,395 underwent gastric bypass and 4,315 underwent sleeve gastrectomy. Outcomes were compared with those of patients without prior GLP-1 treatment, approximately 40,000 gastric bypass patients, and more than 87,000 sleeve gastrectomy patients. Data from 2019 to 2025 was extracted from the Epic Cosmos database.
The study also found that patients who used GLP-1 preoperatively were more likely to resume drug treatment afterwards, but the odds were lower for gastric bypass patients than for those who underwent sleeve gastrectomy at 1 year (44.1% vs. 57.4%). By 3 years, approximately two-thirds of all patients were back on GLP-1. The researchers noted that this suggests that starting GLP-1 treatment before surgery increases the likelihood of long-term use or resuming use postoperatively, whereas patients who proceed directly to surgery may be less likely to require lifelong medication.
Metabolic and bariatric or weight loss surgeries, such as gastric bypass and sleeve gastrectomy, have been shown to be the most effective and long-term treatments for severe obesity. This surgery can improve or resolve conditions such as type 2 diabetes, heart disease, and high blood pressure, leading to significant and lasting weight loss. Its safety profile is comparable to some of the safest and most commonly performed surgeries in the United States, including gallbladder surgery, appendectomies, and knee replacements.
“As the use of GLP-1 drugs continues to increase, it is important for patients and healthcare providers to understand how these therapies fit into broader treatment pathways, particularly for individuals who may benefit from metabolic and bariatric surgery,” said Richard M. Peterson, MD, FASMBS, president of ASMBS and professor of surgery at UT Health San Antonio in Texas. He was not involved in this study. “While drug therapy may begin the path to weight loss, surgery remains the most effective and long-lasting treatment for most patients with severe obesity.”
Currently, less than 1% of people eligible for weight loss surgery undergo weight loss surgery in any given year, according to ASMBS. According to the latest estimates, more than 270,000 bariatric surgeries were performed in 2023.
sauce:
American Society of Metabolic and Bariatric Surgery
