INS and obesity due to melanocortin 4 receptor deficiency: Cyp8b1-/- mice are resistant to diet-induced obesity and have increased energy expenditure, glucose tolerance and insulin sensitivity [80]; mice deficient in Aldh1a1 are resistant to diet-induced obesity, have lower fasting plasma glucose concentration and enhanced oxygen consumption [81, 82]; Thrsp-/- mice have a reduced rate of weight gain, less fat mass, and increased glucose tolerance and insulin sensitivity [83]; and THRSP promotes hepatic lipogenesis [84].