Factors associated with poor weight loss after surgery revealed

04/30/2009 - Articles

Factors associated with poor weight loss after surgery revealed

By: Susan Aldridge, medical journalist, PhD


Some patients do not lose weight effectively after bariatric surgery. A study of a group undergoing gastric bypass surgery has now revealed that having diabetes and having a larger stomach pouch left after surgery are associated with a less successful weight loss result.

Factors associated with poor weight loss after surgery revealed

Summarized by Susan Aldridge, PhD, medical journalist
October 10, 2008


Bariatric (weight loss) surgery is increasing in popularity as a solution to obesity. For most patients, a useful amount of body weight is lost, resulting in resolution of health problems and an improvement of quality of life. But, for some, weight loss is disappointingly small. A review of a group of patients shows that having diabetes and creation of a larger stomach pouch are linked with poor results.


Roux-en-Y gastric bypass is the most common bariatric operation performed in North America. Done in a high-volume center and when there are no complications, an excellent result in terms of weight loss can be anticipated. Weight reduction occurs through reduction of food intake imposed by creation of a smaller stomach pouch during the operation and by creating a bypass of much of the alimentary canal below the stomach. But between five and 15 percent of patients have a disappointing result, losing only a small amount of weight despite apparently successful surgery. A number of reasons have been put forward for this, including greater initial weight, diabetes, insurance status and so on. To clarify the situation, and so help patients to a better outcome, a team at the University of California has reviewed outcomes for a group of patients undergoing Roux-en-Y surgery.

What was done

Doctors at the University of California, San Francisco, looked at data from 361 patients undergoing gastric bypass between 2003 and 2006. The recorded their health status, size of pouch created by the surgeon, and the extent of their weight loss following surgery. They further analyzed 12 month follow-up data for 310 of the patients who had an average body mass index of 52 before surgery.

What was found

The researchers defined good weight loss as losing more than 40 percent of their body weight in the 12 months after surgery. Poor weight loss was losing 40 percent of less of body weight in the same time. At follow up, this group had lost an average of 60 percent of their body weight and ended up with a body mass index of 34. A total of 38 patients had poor weight loss. Having diabetes, and having a larger size of stomach pouch created during surgery were the two most significant factors in getting a poor result.

What this study means

The researchers suggest that diabetes medication like insulin may mitigate against weight loss in various ways. It also appears that having a smaller stomach pouch is crucial. These factors can be dealt with. First, adjustment of diabetic medication may help. Second, standardization of surgical techniques may help a smaller stomach pouch be created as routine. Some surgeons estimate the pouch size using anatomical landmarks, when they could actually use a sizing pouch to be more sure of the result they will get. These improvements could increase the numbers getting a good result from gastric bypass surgery.


  • Factors associated with weight loss after gastric bypass CM. Campos, C. Rabl,  et al., Archives of Surgery, September 2008, vol. 143, pp. 877--884


Created on: 10/10/2008
Reviewed on: 04/30/2009

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