A less common form of obesity surgery may spur more weight loss than its far more popular cousin, gastric bypass - but at the price of greater long-term risks, researchers reported Tuesday.

The study, published in the Annals of Internal Medicine, followed 60 severely obese patients who were randomly assigned to either gastric bypass surgery or a more extensive procedure known as duodenal switch.

Two years after surgery, duodenal switch patients had lost more weight: about 50 pounds more, on average.

People shed a substantial amount of weight with either type of surgery. Gastric bypass patients cut an average of 111 pounds, while duodenal switch patients dropped about 162.

But those extra pounds came with nearly double the complication rate.

Of the 29 duodenal switch patients, 62 percent had problems like abdominal pain, vomiting, diarrhea and intestinal obstruction. And several suffered long-term malnutrition - something not seen in the gastric bypass group.

Duodenal switch is not a popular procedure. In a 2008 study, it accounted for just 1 percent of weight-loss, or bariatric, surgeries done in the U.S., and 5 percent in Europe.

The technique is often reserved for “superobese” patients with a body mass index (BMI) of 50 or higher - though some surgeons perform it with less severely obese patients too, explained Dr. Torgeir T. Sovik of Oslo University in Norway, the lead researcher on the new study.

“As duodenal switch can be associated with more adverse events, this procedure should only be performed in carefully selected patients by a dedicated bariatric team,” Sovik told Reuters Health in an email. “And a closer follow-up after surgery is required after such procedures.”

But an expert not involved in the study went further.

“This is an operation that should probably go away,” said Dr. Edward H. Livingston, a professor and surgeon at the University of Texas Southwestern Medical Center in Dallas.

The average weight loss seen with either gastric bypass or duodenal switch will improve or reverse obesity-related ills like diabetes, sleep apnea and knee arthritis, according to Livingston, who wrote an editorial published with the study.