Gut microbes also partly explain the remarkable success of gastric bypass surgery: a radical operation that reduces the stomach to an egg-sized pouch and connects it directly to the small intestine. After this procedure, people tend to lose dozens of kilograms, a fact typically accredited to their shrunken stomachs. But the operation also restructures the gut microbiome, increasing the numbers of various species, including Akkermansia. And if you transplant these restructured communities into germ-free mice, those rodents will also lose weight.
