Weight loss surgery extends lifespan

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Released: Thursday, August 23, 2007

BATON ROUGE – Gastric bypass and other abdominal surgeries – means of helping severely obese individuals lose large amounts of weight – have gained in popularity as more people see their relatively immediate success in individuals wanting to lose 50, 60 or more pounds. Now, new evidence shows these surgeries may be extending or saving lives.

Lars Sjöström, M.D., Ph.D., and Claude Bouchard, Ph.D., of the Pennington Biomedical Research Center, were members of an international research team that tracked more than 4,000 obese individuals for upwards of ten years. About half of the individuals underwent bariatric surgery (the general term for various forms of weight loss surgery), the other half received conventional treatments. The researchers have concluded that, “bariatric surgery for severe obesity appears to be associated with long-term weight loss and decreased overall mortality.”

Those results are published in the August 23rd issue of The New England Journal of Medicine and, according to the researchers, is the first major report to confirm that weight loss of this magnitude decreases mortality. To the contrary, according to the researchers, some studies had reported in the past that weight loss was associated with increased mortality.

“This was an interventional study,” said Bouchard, “meaning we enrolled obese patients into the study who had sought surgery and compared them to a similar group who were undergoing conventional treatment during the same time frame. Previous studies were based on much smaller sample sizes, with shorter follow-up periods and did not have the proper control group for comparison. What we learned is that an often controversial method - surgery - presents clear clinical evidence of being beneficial.”

Bouchard said one scientific limitation is that ethically, it is not possible to randomly assign subjects into a surgery group or a non-surgery group. The study compared individuals who had made their treatment decisions individually, so the study examined self-selected groups rather than randomized groups, a situation that is not likely to change in studies of this type.

Led by Lars Sjöström, professor at the University of Gothenburg Medical Center and an adjunct and visiting professor at the Pennington Biomedical Research Center, the researchers examined 4,047 obese subjects in a long-term study called the Swedish Obese Subjects (SOS) study. 2,010 underwent bariatric surgery in one of three forms: gastric bypass, vertical-banded gastroplasty or banding while 2,037 subjects received conventional weight loss treatments. The researchers then tracked the weight, behavior and health indicators of the subjects for an average of 11 years.

The average 11-year weight loss of the non-surgery group was less than 2-percent, while the average weight loss among the three surgical groups ranged from 14 to 25-percent.

During the study, researchers recorded 129 deaths in the non-surgery group and 101 in the surgery group, most commonly caused by myocardial infarction and cancer. This result indicates a 23-percent reduction in total mortality within the surgical groups. “We count these results as a milestone in our understanding of the benefits of bariatric surgery for obesity,” Bouchard said. “We are confident in the results and believe this will lead to an acceptance that bariatric surgery is a viable, life-saving option for severely obese patients.”


The Pennington Biomedical Research Center is at the forefront of medical discovery as it relates to understanding the triggers of obesity, diabetes, cardiovascular disease, cancer and dementia. It is a campus of Louisiana State University and conducts basic, clinical and population research. The research enterprise at Pennington Biomedical includes approximately 80 faculty and more than 25 post-doctoral fellows who comprise a network of 44 laboratories supported by lab technicians, nurses, dietitians, and support personnel, and 13 highly specialized core service facilities. Pennington Biomedical's more than 500 employees perform research activities in state-of-the-art facilities on the 222-acre campus located in Baton Rouge, Louisiana.