This study investigates the molecular mechanisms underlying the therapeutic effects of vertical sleeve gastrectomy (VSG), a bariatric surgical procedure. The authors hypothesize that the benefits of VSG, such as weight loss and improved glucose tolerance, are not solely due to mechanical restriction but also involve changes in bile acid signaling and gut microbial communities. They find that VSG increases circulating bile acids and alters gut microbial communities. In knockout mice lacking the nuclear receptor FXR, which is known to regulate bile acid signaling, VSG fails to maintain weight loss, suppress rebound hyperphagia, or improve glucose tolerance. The study suggests that FXR signaling is crucial for the metabolic benefits of VSG, providing a new target for therapeutic interventions.This study investigates the molecular mechanisms underlying the therapeutic effects of vertical sleeve gastrectomy (VSG), a bariatric surgical procedure. The authors hypothesize that the benefits of VSG, such as weight loss and improved glucose tolerance, are not solely due to mechanical restriction but also involve changes in bile acid signaling and gut microbial communities. They find that VSG increases circulating bile acids and alters gut microbial communities. In knockout mice lacking the nuclear receptor FXR, which is known to regulate bile acid signaling, VSG fails to maintain weight loss, suppress rebound hyperphagia, or improve glucose tolerance. The study suggests that FXR signaling is crucial for the metabolic benefits of VSG, providing a new target for therapeutic interventions.