An insightful new study published in the Journal of the American Medical Association (JAMA) presents evidence that two well-known surgical procedures intended to help obese patients lose weight produce nearly identical results in terms of changes to body mass index (BMI) 5 years following the procedures.

The research, conducted by the Swiss Multicenter Bypass or Sleeve Study, followed 217 morbidly obese patients that were evaluated for bariatric surgery from January 2007 to November 2011. From this group, 107 patients were advised to undergo laparoscopic sleeve gastrectomy and 110 received laparoscopic Roux-en-Y gastric bypass. Sleeve gastrectomy, considered a faster, less technically complex surgery, involves removing approximately 85% of the stomach by excising a large portion of the organ along its greater curvature. In contrast, Roux-en-Y is a more time-intensive and complex operation in which the stomach is reduced to a very small pouch that is directly attached to the jejunum of the small intestine. Then the intestinal section of the stomach and duodenum that is severed is sewn shut at the stomach’s esophageal end and also attached to the jejunum at the duodenal end creating the “Y” junction that it is characterized by. In this manner, ingested food passes through a much smaller stomach pouch however the larger, separated stomach remnant is still able to provide important gastric enzymes to aid in the process of digestion.

Five years post procedure, the patients who underwent sleeve gastrectomy reported a reduction in their excess BMI of 61.1% and patients who underwent Roux-en-Y reported a reduction of 68.3%, indicating that both operations achieved almost the exact result in terms of weight loss. This can be interpreted as significant since despite the fact that sleeve gastrectomies are being carried out with increasing frequency, there is currently little evidence that shows that they are effective in the long term.

One notable exception to the general conclusion that results obtained from both procedures were relatively similar is that patients who underwent sleeve gastrectomy were more likely to continue to suffer from Gastrointestinal Reflux Disease (GERD) or even experience worsening of the disease symptoms. In examining how the two procedures are carried out, one might have hypothesized that this could be a possible finding given that in a sleeve gastrectomy, the general structure of the stomach and midgut remains intact, which could allow existing reflux issues to remain. In comparison, in a Roux-en-Y procedure, the stomach is reduced to an egg-sized pouch and the vast majority of the gastric-enzyme producing stomach is disconnected from the esophagus thus theoretically lessening the potential of gastric juices to reflux into the esophagus.

Another important finding in this study was that neither procedure could be shown to provide an advantage in remission rates of type II diabetes. The Swiss team cited other studies showing that Roux-en-Y typically provides a superior rate of diabetes remission in patients in the long term when compared to sleeve gastrectomy. However, no evidence could be found in the current study to support this conclusion.


Peterli R, Wolnerhanseen BK, Peters T, et al. Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity The SM-BOSS Randomized Clinical Trial. JAMA. 2018;319(3):255-265.

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