TUESDAY, Aug. 11, 2015 (HealthDay News) -- In a finding that may help to explain why weight loss can be sustained after gastric bypass surgery, scientists report that the procedure boosts the amount of calories that people burn while eating a meal.
"Parts of the small intestine become more active and require additional nutrition after a gastric bypass. As a result, the blood absorbs fewer nutrients to store as fat. You might say that people burn calories by eating," study author Malin Werling, from the Sahlgrenska Academy at the University of Gothenburg in Sweden, said in a university news release.
Gastric bypass reroutes food past the stomach directly to the small intestine, which means people become full sooner than normal, resulting in weight loss.
But reduced food intake alone couldn't fully explain how the surgery helps people keep weight off over the long term, the researchers said. To find answers, they assessed the metabolism of gastric bypass patients for up to two years after the procedure.
The results showed that the surgery caused a sharp increase in the amount of calories burned during meals.
The study was recently published in the journal PLoS One.
Experts had already known that eating requires an increase in the body's energy demands because the gastrointestinal tract requires energy to break down and absorb nutrients. But, what wasn't known was the degree that gastric bypass surgery increases this demand, the researchers said.
Further research to learn more about why the surgery has this effect could lead to new drugs that do the same thing, the study authors said.
The American Society for Metabolic and Bariatric Surgery has more about weight-loss surgeries .