The weight-loss surgery called vertical sleeve gastrectomy reduces the stomach to the size of a banana. The idea is that a person will feel full sooner because they have less room to take in food.
However, a new study in mice suggests that the value of the stomach-shrinking surgery actually comes from having more gastric juices swirling around a smaller space and a change in the gut microbiome, researchers report March 26 in Nature. The team identified one bile acid molecule, called FXR, that appeared to play a critical role in sustaining weight loss. The finding could lead to less invasive ways to counter obesity, the scientists suggest.