GCG and obesity due to melanocortin 4 receptor deficiency: In this context, it was shown that dietary bile acids [49] and activation of the bile acid receptors TGR5 in adipose tissue and FXR in intestine but not in liver [45, 50, 51] increases secretion of GLP-1, insulin sensitivity, energy expenditure, UCP1 activity and browning of white adipose tissue, thereby counteracting obesity.