GPBAR1 and obesity due to melanocortin 4 receptor deficiency: Gut microbiota-derived LCA activates TGR5 (which is expressed in enteroendocrine L cells) and induces the expression of the gene encoding TGR5, resulting in increased secretion of glucagon-like peptide 1 (GLP-1), thereby improving insulin sensitivity and reducing obesity through white adipose browning [72, 80, 81].