INS and obesity due to melanocortin 4 receptor deficiency: Indeed, recently it has been proven that SCD1 deficient mice (Scd1−/−) exhibit enhanced energy expenditure, improved insulin sensitivity of skeletal muscle, and high resistance to diet-induced weight gain, which collectively highlight the close link between SCD1 overactivity and obesity occurrence (Dobrzyn et al., 2005; Miyazaki et al., 2007).