That’s where Peter Turnbaugh came in. Then a graduate student in the lab, he harvested microbes from fat and lean mice, and then fed them to germ-free rodents. Those that got microbes from lean donors put on 27% more fat, while those with obese donors packed on 47% more fat. It was a stunning result: Turnbaugh had effectively transferred obesity from one animal to another, simply by moving their microbes across. “It was an ‘Oh my God’ moment,” said Gordon. “We were thrilled and inspired.”……..
They can also turn it in both directions. While Turnbaugh showed that gut microbes can lead to weight gain, others have found that they can trigger weight loss. Akkermansia muciniphila, one of the more common species of gut bacteria, is over 3,000 times more common in lean mice than in those genetically predisposed to obesity. If obese mice eat it, they lose weight and show fewer signs of type 2 diabetes.