LOS ANGELES — People who undergo gastric bypass surgery at the same time as a family member are likely to succeed far better than people who undergo the surgery alone, according to a study released at the annual meeting of the American Society for Metabolic & Bariatric Surgery.

Prior research shows having an exercise partner helps people stick to their workout regimen and accrue greater health benefits from exercise. It appears the same dynamic can work for people having bariatric surgery. Researchers from the University of Medicine and Dentistry in New Jersey-Robert Wood Johnson Medical School followed 91 patients from 41 families who had surgery with a sibling, parent, child, spouse, cousin, grandmother, granddaughter, in-law, aunt, uncle, nephew or niece. They were compared with similar patients who had surgery alone.

After one year, the family members lost, on average, about 30 percent more of their excess weight than did the control group. Siblings, in particular, fared especially well. They lost about 40 percent more of their excess weight compared with the control group.

"Clearly the family dynamic, even a little sibling rivalry, can play an important role in patient success," the lead author of the study, Dr. Gus J. Slotman, said in a news release. "Family members are a built-in support system that can help turn a good result into a great result, particularly the first year after surgery, when adjusting to a new lifestyle and dietary requirements can be challenging."

In another study presented at the meeting, researchers found female patients have fewer complications and shorter hospital stays compared with male patients undergoing laparoscopic gastric bypass. The study of nearly 38,000 people also showed Latinos and Caucasians have fewer complications than African-Americans, and younger patients do better than older ones. The research was performed at the University of Nebraska Medical Center.