Some people who are severely obese and have gastric bypass surgery may be able to keep weight off for six years, giving them reduced risks of cardiovascular problems and diabetes, a U.S. study finds.

The study focused on 1,156 adults with a body mass index of 35 or higher — which is considered severely obese — and who had the bypass surgery. They were compared with 739 other severely obese people in two groups who did not get the surgery.

"At six years, 96 per cent of surgical patients had maintained more than 10 per cent weight loss from baseline and 76 per cent had maintained more than 20 per cent weight loss," Ted Adams of the University of Utah School of Medicine and his co-authors wrote in Tuesday’s issue of the Journal of the American Medical Association.

All cardiovascular risk factors improved or stayed the same among those who received a type of gastric bypass surgery called Roux-en-Y compared with those who did not, Adams said.

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People in the Utah study received a type of gastric bypass surgery called Roux-en-Y. (Paul Sakuma/Associated Press)

Other differences at the end of the study included:

  • Mortality rate three per cent for surgery patients, three per cent for obese patients who were evaluated and one per cent among the control group of obese adults.
  • Diabetes remission 62 per cent for surgery, eight per cent in control group 1 and six per cent in control group 2.

Of the 29 deaths in total, four suicides and two of three poisonings were among those who had the surgery, Dr. Anita Courcoulas of the University of Pittsburgh Medical Center said in a journal commentary accompanying the study.

"The mortality rates in this study were too small to assess statistically, but serve as reminder of an uncommon but important outcome needing objective monitoring."

Surgery wait lists in Canada

The death rate for gastric bypass surgery is similar to that of gall bladder surgery, said Dr. Raj Padwal, an epidemiologist and internist at the University of Alberta in Edmonton

In Canada between 2007 and 2009, an estimated 1.5 million obese Canadian adults met eligibility criteria for bariatric surgery, yet less than one per cent actually received it, said Padwal, who co-authored a study on publicly funded bariatric surgery. The study is in Tuesday's online issue of the International Journal for Equity in Health.

When someone's weight reaches around 250 pounds to 300 pounds, in some cases the surgery is medically necessary given the risk of other illnesses, Padwal said. The question is should it be publicly funded, given that elective surgery is often the first to be cut, he added.

"It has confirmed that bariatric surgery saves lives," said Montreal surgeon Dr. Nicolas Christou, who performed the first elective laparoscopic gastric bypass in Canada in 2002. "The way it does it is by controlling obesity-associated diseases that eventually will kill people."

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Heather McInnis's Type 2 diabetes was resolved following gastric bypass surgery in 2008. (CBC)

Longer-term research is needed to answer questions about how gastric bypass can lead to malabsorption of nutrients and bone disease, Padwal said.

Heather McInnis, 57, of Chateauguay, Que., had gastric bypass surgery in 2008 when she weighed 347 pounds. Before the surgery, McInnis said she had Type 2 diabetes and high blood pressure despite trying every diet she could.

"I would go in a grocery store and fill my cart and leave it because the pain in my legs and back were so bad," she recalled. A week after the surgery, McInnis had a leakage complication and was put back in the hospital for a month to take saline water and antibiotics. She's been fine since going from a size 5X to a size 5, now weighing in at 152 pounds.

"I've saved the government a lot of money," on treating health complaints, she said. "I don't even see doctors anymore. Maybe once a year to check my cholesterol, check my calcium."

In the study, none of the death occurred with 30 days after surgery.

A 20-year study of bariatric surgery patients called the Swedish Obese Subjects study also showed an average of seven per cent weight regain among people having gastric bypass surgery, Adams' team said.

The study was funded by the U.S. National Institutes of Health, National Institutes of Diabetes and Digestive and Kidney Diseases and the National Center for Research Resources.

With files from CBC's Kelly Crowe and Pauline Dakin