External or internal circadian system desynchrony has been associated with diverse metabolic dysfunctions, including compromised glucose tolerance and diminished insulin sensitivity, elevated susceptibility to complications related to reduced insulin sensitivity, such as non-alcoholic fatty liver disease (NAFLD), heightened levels of proinflammatory cytokines, elevated arterial blood pressure, and decreased energy expenditure, leading to obesity [40,41,42]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.