GPR120, which is expressed in both islet and in enteroendocrine cells, is activated by medium- and long-chain fatty acids (LCFAs) and has been extensively investigated as a drug target for treatment of obesity and type 2 diabetes due to its many effects on metabolism including increasing secretion of GLP-1 [28, 29]. This evidence concerns the gene FFAR4 and obesity due to melanocortin 4 receptor deficiency.