A small comparative analysis found that a procedure called biliopancreatic diversion with duodenal switch (or simply "duodenal switch") seems to lead to greater weight loss than traditional gastric bypass surgery. In addition, duodenal switch patients had a bigger drop in cholesterol, triglycerides and blood sugar levels.

"Five years after surgery, the average reductions in weight were 41 kilograms [90 pounds] after gastric bypass and 66 kilograms [145 pounds] after duodenal switch," said study co-author Dr. Torsten Olbers, an assistant professor of surgery at Sahlgrenska University Hospital in Gothenburg, Sweden.

But "patients who underwent duodenal switch also had more subsequent surgical procedures related to the initial operation, and more hospital admissions for nutritional complications, compared to patients who underwent gastric bypass," Olbers added.

The study findings were published in the Feb. 4 online edition of JAMA Surgery.

According to the American Society for Metabolic and Bariatric Surgery, gastric bypass is currently considered the gold standard of weight loss (or "bariatric") procedures, and is the most common such surgery. It involves dividing and reconnecting portions of both the stomach and the small intestine to create a smaller stomach pouch, while re-directing the food absorption pathway.

By contrast, the duodenal switch procedure entails the removal of a portion of the stomach and bypassing a large portion of the small intestine, the society explained.

To explore the pros and cons of each, the study team focused on 60 patients aged 20 to 50.

Their average weight was around 355 pounds, according to the study. That translates to an average body mass index (BMI) of between 50 and 60. Anyone with a BMI in excess of 40 is considered to be severely obese, according to the U.S. Centers for Disease Control and Prevention.

About half the patients underwent standard gastric bypass surgery, while the other half underwent the duodenal procedure. In the end, 55 patients were tracked for five years.

The result: by the five-year mark the gastric bypass group shed an average of nearly 14 BMI points, while the duodenal group shed more than 22 points.

The researchers also found that blood pressure, lung function and the incidence of type 2 diabetes were similar among the two groups, as was overall quality of life. But, the duodenal group showed greater reductions in cholesterol, triglycerides, and fasting blood sugar levels.

However, those in the duodenal group were also prone to a much higher risk for nutritional complications, gastrointestinal problems and re-hospitalization. Almost 80 percent of duodenal patients experienced one or more complications during the post-surgery timeframe. That compares to 68 percent in the gastric bypass group, according to the study.

While less than 10 percent of the gastric bypass group had to undergo more surgical procedures as a result of their initial operation, that figure rose to nearly 45 percent among the duodenal group, the researchers found.

Olbers and his colleagues concluded that, despite its apparent superiority as a means to help obese patients lose weight, the "duodenal switch should be used with caution."

This point was seconded by a pair of University of Michigan researchers, who stated in a journal editorial that "the benefits of undergoing duodenal switch hardly seem worth the sacrifice when compared with gastric bypass."

Dr. Mitchell Roslin, chief of bariatric and metabolic surgery at Lenox Hill/North Shore-LIJ Health System Hospital in New York City, argued that the more important message is that "gastric bypass is just not an adequate therapy for many patients."

Roslin said, "I really believe that the conclusion this team draws is way too in favor of gastric bypass. Their thinking makes light of weight loss, which is the goal of any of these procedures. And more than half the gastric bypass patients remained morbidly obese at the five-year point, a figure that I guarantee would go precipitously higher if you take another look five years later," he added.

"Now yes, it's true that you have to be concerned that duodenal switch [surgery] may be too powerful for some patients. But gastric bypass just doesn't work well. So the goal should be to try and find a balance by modifying the duodenal procedure to minimize the harsh effects and maximize outcomes, which is something I and others are working to do right now," Roslin said.