Here, the authors show that β-Klotho KO mice have a high production of CA in liver, resulting in an important excess of DCA (secondary BA) production by microbiota, suggesting that resistance of these KO mice to diet-induced obesity is mainly caused by the high production of DCA and its signaling through the receptor TGR5 (Somm et al., 2017). This evidence concerns the gene KLB and obesity disorder.