New UCL research supports use of the weight loss drug semaglutide for patients who do not get enough benefit from bariatric surgery.
Metabolic/bariatric surgery is a highly effective treatment for people living with severe obesity and/or metabolic health conditions, which works through changing the anatomy of the digestive system and thereby changing the way it functions and the hormones it produces. Procedures include the sleeve gastrectomy and gastric bypass.
However, around one in five people who have bariatric surgery either do not lose enough weight or regain weight afterwards. With around 500,000 bariatric surgeries taking place around the world each year, there is a large need for alternative treatments for this group.
Previously, options for patients who responded sub-optimally to bariatric surgery were lifestyle intervention - which had limited benefit - or further surgery - which had increased surgical risk, was invasive, and was only available to a minority of patients.
Published in Nature Medicine , the BARI-STEP trial, led by Dr Janine Makaronidis at the UCL Centre for Obesity Research, looked at use of semaglutide at a dose of 2.4mg in patients who had not responded well to bariatric surgery.
A similar medicine, liraglutide, has previously shown some benefit in this group, but earlier research found semaglutide produced greater weight loss. BARI-STEP is the first randomised controlled trial of semaglutide in patients following bariatric surgery.
The study involved 70 patients recruited from University College London Hospitals and Homerton University Hospital. Participants took part for 68 weeks and were randomly assigned to receive either semaglutide or a placebo injection. Both groups also received lifestyle advice and support with a reduced-calorie diet.
Among patients taking semaglutide:
Researchers found that most of the weight loss came from body fat rather than muscle.
The semaglutide group also showed improvements in blood sugar levels, cholesterol and other measures linked to heart and metabolic health. Patients also reported better quality of life.
The side effects seen in the study were already well known from previous semaglutide research, including nausea and reduced appetite.
Dr Makaronidis said: “These findings strengthen the case for using semaglutide in people who do not respond well to bariatric surgery, offering an alternative to repeat operations. They also suggest that combining surgery with weight-loss medicines is an important approach to treating severe obesity.
“As next steps, we need larger and longer studies involving more diverse groups of patients. We would also like to investigate whether semaglutide could help patients before surgery as well as afterwards.”
The study was supported and co-funded by the NIHR University College London Hospitals Biomedical Research Centre.
ENDS
Nature Medicine
Randomized controlled/clinical trial
People
Semaglutide vs placebo in individuals with poor weight-loss following bariatric surgery: a double-blinded, randomised, placebo-controlled trial
22-May-2026