Roux-en-Y Gastric Bypass and Vertical Banded Gastroplasty Induce Long-Term Changes on the Human Gut Microbiome Contributing to Fat Mass Regulation

TLDR

Bariatric surgery is currently the most effective treatment for obesity. The study examined the long‑term effects of Roux‑en‑Y gastric bypass and vertical banded gastroplasty on the gut microbiome in patients matched for weight and fat mass loss. The authors colonized germ‑free mice with patient stool samples to show that the altered microbiota promoted reduced fat deposition. Both procedures induced durable, BMI‑independent microbiome changes that altered fecal and circulating metabolites, and when transferred to mice, the microbiota reduced fat deposition and lowered respiratory quotient, indicating a direct role in post‑surgical adiposity reduction.

Abstract

Bariatric surgery is currently the most effective procedure for the treatment of obesity. Given the role of the gut microbiota in regulating host metabolism and adiposity, we investigated the long-term effects of bariatric surgery on the microbiome of patients randomized to Roux-en-Y gastric bypass or vertical banded gastroplasty and matched for weight and fat mass loss. The two surgical procedures induced similar and durable changes on the gut microbiome that were not dependent on body mass index and resulted in altered levels of fecal and circulating metabolites compared with obese controls. By colonizing germ-free mice with stools from the patients, we demonstrated that the surgically altered microbiota promoted reduced fat deposition in recipient mice. These mice also had a lower respiratory quotient, indicating decreased utilization of carbohydrates as fuel. Our results suggest that the gut microbiota may play a direct role in the reduction of adiposity observed after bariatric surgery.