Fibroblast growth factor 19 (FGF19) is a secreted protein which belongs to the FGFs family. FGF19 is expressed in fetal brain, cartilage, retina, and adult gall bladder. FGFs modulate cellular activity via at least 5 distinct subfamilies of high-affinity FGF receptors (FGFRs): FGFR-1, -2, -3, and -4, all with intrinsic tyrosine kinase activity. FGFRs can be important for regulation of glucose and lipid homeostasis. FGF19 has important roles as a hormone produced in the ileum in response to bile acid absorption. It has been shown to cause resistance to diet-induced obesity and insulin desensitization and to improve insulin, glucose, and lipid profiles in diabetic rodents. FGF19 can be considered as a regulator of energy expenditure.