In the race to treat obesity, surgery remains the most effective option. A new study from New York University shows that bariatric surgery results in significantly more weight loss than the latest GLP-1 medications, such as Ozempic and Wegovy, even though those drugs have transformed obesity treatment in recent years.
The study, released this week, analyzed real-world medical records from thousands of patients. It found that, on average, people who underwent weight-loss surgery lost five times more weight over two years than those prescribed GLP-1 drugs.
Real-World Results Paint a Different Picture
Dr. Karan Chhabra, a bariatric surgeon and assistant professor at NYU Grossman School of Medicine, led the research. He emphasized that new drug results should always be evaluated cautiously.
“When a new drug becomes popular, it’s important to wait for real-world data. Clinical trials often don’t reflect what happens outside the lab,” Chhabra told Gizmodo.
Bariatric surgery—especially procedures like sleeve gastrectomy and gastric bypass—has long been considered the gold standard in obesity treatment. Patients often lose 20% to 30% of their body weight and see lasting improvements in their overall health.
GLP-1 drugs, such as semaglutide and tirzepatide, have become widely used alternatives. In clinical trials, they helped patients lose between 10% and 20% of their body weight, making them more effective than previous nonsurgical treatments. These drugs have also shown benefits beyond weight loss, including improvements in blood sugar and heart health.
But until now, researchers had not closely compared surgical and GLP-1 outcomes in everyday healthcare settings.
Over 50,000 Cases Examined
To conduct the study, Chhabra and his team analyzed the anonymized medical records of more than 50,000 patients treated at NYU Langone Health and NYC Health + Hospitals from 2018 to 2024. These patients had either undergone bariatric surgery or been prescribed GLP-1 medications like semaglutide or tirzepatide.
The researchers accounted for variables such as age, starting body mass index (BMI), and pre-existing health conditions to make comparisons fair. Each patient’s weight loss was tracked for two years.
Surgical patients lost an average of 58 pounds—about 24% of their body weight. GLP-1 users, by contrast, lost just 12 pounds, or roughly 4.7% of their weight. Even among those who stayed on their medication for a full year, average weight loss only reached 7%. Those taking tirzepatide, the most potent GLP-1 drug, saw slightly better results—8% to 9%—but still well below the average weight loss seen with surgery.
The findings were presented at the annual meeting of the American Society for Metabolic and Bariatric Surgery (ASMBS).
Why the Discrepancy?
Chhabra offered several reasons why GLP-1 medications perform worse in practice than in trials. A major issue is patient adherence: up to 70% of users stop taking the drugs within the first year. Some experience side effects like nausea and diarrhea; others discontinue due to high costs, with monthly prices exceeding $1,000 when insurance doesn’t cover them.
The study also found that many patients never reached the full therapeutic dose of the medication. And unlike participants in clinical trials, real-world patients often receive less consistent medical follow-up and support.
“Many people are prescribed GLP-1 drugs via telemedicine without ever meeting the doctor in person,” Chhabra noted. “That lack of support can affect outcomes.”
Until recently, some patients also used compounded versions of semaglutide and tirzepatide, which may be less reliable than branded drugs.
No One-Size-Fits-All Solution
Chhabra stressed that the study does not mean people with obesity shouldn’t consider GLP-1 drugs. Nor does it suggest that surgery is the right choice for everyone.
GLP-1 therapy may be a better option for those who prefer a non-invasive approach or can’t afford surgery. Some may also avoid surgery due to health risks or personal concerns. But Chhabra advises patients to be realistic about what these treatments can offer.
“They need to understand that, in the real world, these drugs don’t match the results seen with surgery,” he said. “And they need to know it’s a lifelong commitment. We still don’t have effective strategies for maintaining weight loss after stopping medication.”
Next Steps in the Research
The research team now plans to dive deeper into the data to learn more about why GLP-1 users are falling short of expectations in routine care. The goal is to improve real-world outcomes for these patients.
