New research, conducted by Stanford scientists in collaboration with researchers at Massachusetts General Hospital, has found that the gut microbes of mice undergo drastic changes following gastric bypass surgery and transfer of these microbes into sterile mice resulted in rapid weight loss.
"Simply by colonizing mice with the altered microbial community, the mice were able to maintain a lower body fat, and lose weight - about 20 percent as much as they would if they underwent surgery," Peter Turnbaugh, a Bauer Fellow at Harvard's Faculty of Arts and Sciences (FAS) Center for Systems Biology, and one of two senior authors of the paper, said.
Turnbaugh said that the mice used in the study hadn't been given a high-fat, high-sugar diet to increase their weight beforehand.
"The question is whether we might have seen a stronger effect if they were on a different diet," he said.
Lee Kaplan, director of the Obesity, Metabolism and Nutrition Institute at MGH and the other senior author of the paper, said "our study suggests that the specific effects of gastric bypass on the microbiota contribute to its ability to cause weight loss and that finding ways to manipulate microbial populations to mimic those effects could become a valuable new tool to address obesity."
While the results were exciting, Turnbaugh said that it may be years before they could be replicated in humans.
While there had been hints that the microbes in the gut might change after bypass surgery, the speed and extent of the change came as a surprise.
"The post-bypass community was dominated by Proteobacteria and Proteobacteria, and had relatively low levels of Firmicutes," Turnbaugh said.
He said that these changes occurred within a week of the surgery, and weren't short-lived - the altered gut microbial community remained stable for months afterward.
The study has been published in Science Translational Medicine.