Bile acids act as biological signaling molecules, whose interactions with some host receptors such as the nuclear bile acid receptor (also known as farnesoid X receptor, FXR) or the bile acid-activated membrane G protein-coupled receptors, TGR5 (aka Gpbar-1, G-protein-coupled bile acid receptor) appear to play a role in stimulating energy metabolism, protecting liver and intestine from inflammation and steatosis, and improving insulin sensitivity, as well as playing a significant role in weight loss [137,138]. The gene discussed is NR1H4; the disease is steatosis.