Which Weight Loss Surgery Has Fewer Early Complications, Sleeve or Bypass?
A 2026 study found that gastric sleeve surgery was linked to a higher rate of early complications than one anastomosis gastric bypass in the first 60 days after the operation. Both procedures had complication rates below 16 in 100 patients, and the difference was moderate rather than dramatic.
Who Was Studied and How
Researchers at a single hospital in Israel reviewed the records of 2,382 patients who had either a gastric sleeve or a one anastomosis gastric bypass between 2009 and 2024. A gastric sleeve reshapes the stomach into a narrow tube, while a one anastomosis gastric bypass makes the stomach smaller and reconnects it further along the digestive tract. To make the comparison as fair as possible, the team carefully matched 1,191 pairs of patients who were similar across a range of characteristics, then looked at any complications occurring within 60 days of surgery.
What the Researchers Found
About 15 in 100 gastric sleeve patients experienced a complication within 60 days, compared with about 12 in 100 one anastomosis gastric bypass patients. Sleeve patients had higher rates of leaks, bleeding, abscess and swallowing difficulties, while bypass patients showed more respiratory complaints and ulcers found by camera examination.
What This Study Does and Does Not Tell Us
The study was carried out at one centre in Israel, relied on historical records rather than a controlled trial, and did not capture care that patients may have received at other hospitals. These factors mean the findings may not apply in every setting, and results can vary from person to person.
About this research: Early 60 Day Morbidity after Sleeve Gastrectomy Versus One Anastomosis Gastric Bypass: A Propensity Matched Single Center Cohort of 2,382 Patients. Published in Obesity Surgery, 2026. Read the study summary
More about this procedure is on our one anastomosis gastric bypass page. If you are considering your options, call us on (03) 9760 2777 or request an appointment through our website.