Combining GLP-1 RA and Bariatric Surgery Ups Weight Loss

SAN FRANCISCO — Patients who use GLP-1 receptor agonists (GLP-1 RAs) both before and after undergoing bariatric surgery experience greater weight loss than with surgery alone, new data suggested.

The real-world study of more than 500 adults who underwent bariatric surgery between 2019 and 2023 at a single institution is believed to be the first to examine both pre- and postoperative use of GLP-1 RAs in the immediate perioperative period surrounding bariatric surgery. Other studies have had varied results and focused on preoperative use only or postoperative use in terms of weight regain, lead author Angela Rao, MD, a recent endocrinology fellowship graduate from Stanford University, Stanford, California, told Medscape Medical News.

The findings suggest that “in the right patient, combining GLP-1RAs with bariatric surgery may lead to improved weight-loss outcomes, as well as expected improvement in other comorbidities. However, this should be balanced with the potential risks of nutritional deficiencies, loss of lean muscle mass, and other considerations such as cost,” Rao said.

She presented the findings at ENDO 2025: The Endocrine Society Annual Meeting.

Study co-author Dan E. Azagury, MD, chief of the Section of Minimally Invasive and Bariatric Surgery at Stanford University and medical director of the Stanford Lifestyle and Weight Management Center, Palo Alto, California , told Medscape Medical News that the study group is “unique in being a joint effort between surgeons, medical weight-loss specialists, and endocrinologists all working together in an integrated clinic. This study is proof of the advantages of combined multidisciplinary management of obesity, being able to tailor treatments to each patient using all of the modalities available depending on the severity of disease, patient preferences, and medical history.”

Asked for comment, session moderator Olena Klindukhova, MD, assistant professor at the Medical College of Wisconsin, Milwaukee, told Medscape Medical News that her center also has endocrine and bariatric surgery “under the same roof” and that she often combines the two modalities in her practice. However, she cautioned, “The biggest limitation is the cost.”

Together Is Better: GLP-1 RAs Before and After Bariatric Surgery Weight Loss

Of 675 patients who underwent bariatric surgical procedures (sleeve gastrectomy or Roux-en-Y gastric bypass) at Stanford Health Care, Stanford, California, between January 1, 2019, and December 31, 2023, 424 had not been prescribed a GLP-1 RA within 2 years before or after surgery (control group). Of the rest, 21 had taken GLP-1 RAs within 2 years prior to surgery but not after (group 1), 68 had used GLP-1 RAs within 2 years after surgery but not before (group 2), and 47 had used GLP-1 RAs within 2 years before and 2 years after surgery (group 3). The remaining 115 were excluded because either the prescription was not filled or the duration of therapy was less than 4 months.

Compared with the control group, those who had used GLP-1 RAs perioperatively had significantly higher baseline BMIs (49.4 vs 45.7; P < .001). Other demographic characteristics didn’t differ, but those who had received GLP-1 RAs were also significantly more likely to have type 2 diabetes (53.7% vs 26.2%; P < .001), hypertension (62.5% vs 46.9%; P = .005), and gastroesophageal reflux (69.9% vs 59.9%; P = .003). 

Total percentage body weight loss, based on the minimum postoperative weight subtracted from the maximum preoperative weight within 2 years of surgery, was 30.3% for bariatric surgery alone (control group), 29.7% for surgery with preoperative GLP-1 RA (group 1), 30.7% for surgery with postoperative GLP-1 RA (group 2), and 33.0% for surgery with both pre- and postoperative GLP-1 RA (group 3). The difference between group 3 and the control group was significant (P < .05).

Thus, the maximum weight loss was achieved by those who were on GLP-1 RAs both before and after bariatric surgery, while neither perioperative use nor preoperative use alone led to significant weight loss compared with the control group, Rao noted, adding that individuals with the highest BMI (> 50) appear to be the most likely to benefit from starting GLP-1 RAs in the preoperative period and continuing postoperatively.

“GLP-1 RA usage in the perioperative period may prime patients for more effective weight loss, potentially by inducing behavioral or physiological changes that complement the metabolic effect of surgery,” she said.

The decision of whether to continue GLP-1 RAs postoperatively “should be individualized and take into account factors including diabetes, cardiovascular disease, and obstructive sleep apnea. This should be balanced with potential risks of nutritional deficiencies and sarcopenia,” Rao advised.

Commenting on the study, Klindukhova said that for preoperative use, she’d like to see additional short-term data on other outcomes such as tolerability and hospital length of stay and to see long-term data for both pre- and postoperative GLP-1 RA use. For patients not already taking them presurgically, “I don’t think I would put them on GLP-1s right after bariatric surgery but would consider doing so sooner rather than later if they’re losing weight too slowly or if they’re behind the curve. This study gives more validation for maybe being a little bit more proactive.”

Rao and Klindukhova reported no disclosures. Azagury reported being a consultant for Form Health, GI Windows Surgical, and Endolumik.

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape Medical News, with other work appearing in the Washington Post, NPR’s Shots blog, and Diatribe. She can be reached on X @MiriamETucker and on BlueSky @miriametucker.bsky.social.