Surgery Outperforms Ozempic and Other GLP-1 Medications in Practical Weight Loss Research

When it comes to weight loss, surgery still reigns supreme. Research out today shows that people undergoing bariatric surgery tend to lose significantly more weight than people taking the newest, most effective GLP-1 medications for obesity.

Scientists at New York University conducted the study, which analyzed real-world data from obesity patients. People who received surgery lost five times more weight over a two year span on average than those who were prescribed a GLP-1 drug, they found. The findings also suggest that GLP-1 drugs aren’t as effective in the real world as they are in clinical trials, the researchers say.

“I think the takeaway is when you see a new popular drug come out, you have to take it with a grain of salt. And I think you have to wait a few years for the real world data to come out, because it might temper the results you’re seeing in trials,” senior study researcher Karan Chhabra, a bariatric surgeon and assistant professor of surgery and population health at the NYU Grossman School of Medicine, told Gizmodo.

Bariatric surgery—particularly the sleeve gastrectomy and gastric bypass—has long been considered the most effective treatment for obesity. People usually lose between 20% and 30% of their baseline weight following surgery, and often experience long-lasting improvements in their general health as a result.

But in recent years, the emergence of newer GLP-1 drugs like semaglutide (the active ingredient in Ozempic and Wegovy) has dramatically changed the field of obesity medicine. These drugs are typically more effective (and safer) than past nonsurgical obesity treatments, with people on average losing between 10% and 20% of their weight in clinical trials. And they, too, have been associated with health benefits that extend beyond weight loss.

At first glance, the data had suggested GLP-1 drugs could approach—or even surpass—the effectiveness of bariatric surgery. But according to Chhabra, there hasn’t yet been a rigorous head-to-head comparison of these two different types of obesity treatments among real-world patients.

Chhabra and his colleagues examined the anonymous medical records of over 50,000 people who received surgery (either a sleeve gastrectomy or gastric bypass) or GLP-1 therapy (either semaglutide or tirzepatide) through NYU Langone Health or NYC Health + Hospitals between 2018 and 2024. The researchers adjusted for factors like age, starting BMI, and other health conditions to make the two groups comparable. The patients and their weight loss outcomes were tracked for two years.

On average, surgical patients lost 58 pounds (around 24% of their total weight) by the end of year two, whereas GLP-1 patients on average lost 12 pounds (around 4.7% of their total weight)—a fivefold difference. The results were slightly better for people who stayed on their medications for a full year (7% weight loss) and for those who took tirzepatide, the newest and most effective GLP-1 drug available (8% to 9%). But the outcomes still fell well short of the success seen with surgery—not to mention the results from earlier clinical trials.

The team’s findings were presented this week at the annual meeting of the American Society for Metabolic and Bariatric Surgery (ASMBS).

There are likely several reasons why these drugs aren’t as successful as they’ve appeared to be in trials, Chhabra noted. As many as 70% of GLP-1 patients discontinue use by the first year, for instance. Some will quit because the side effects, typically gastrointestinal symptoms like nausea and diarrhea, are too much to bear; others may stop simply because they can’t afford the drugs any longer (GLP-1 medications often aren’t covered by insurance and can cost upwards of $1,000 a month without coverage). Many of the GLP-1 patients in their study also never reached the maximum dose.

Chhabra also suspects that many people in the real world aren’t getting the supportive care and follow-up they would get from doctors in a clinical trial. GLP-1 drugs have fueled a growing telemedicine industry—for instance, one in which people are often prescribed the medications remotely by medical professionals they’ll never interact with personally. (Until recently, people could also easily get compounded versions of semaglutide and tirzepatide, with even less assurance of safety or effectiveness.)

The researchers aren’t saying that people with obesity shouldn’t take GLP-1 drugs, nor that bariatric surgery is the ideal option for everyone. Some people might prefer a one-time treatment, for instance, or may not have the insurance or resources needed to cover long-term GLP-1 therapy. Others may be nervous about going through with any invasive procedure or have other pre-existing conditions that could complicate surgery but not GLP-1 therapy.

At the end of the day, people will need to be aware of these treatments’ respective pros and cons, and those who choose to go with GLP-1s should manage their expectations, according to Chhabra.

“They have to know that, at least as of now in the real world, their weight loss is not going to be what we’re seeing with surgery and they also have to know that it’s a lifelong treatment,” he said. “We don’t yet have any protocols for people to maintain weight loss once they’ve stopped medications so it’s important for people to just acknowledge those realities. And I worry that a lot of people are starting medications without really knowing what they’re getting into.”

The team next plans to sift through more data to figure out exactly why real-life patients on GLP-1 therapy aren’t losing as much weight as expected.