Under similar dietary conditions, plasma concentrations of glucagon, GLP-1 and GIP were found to be higher in the daytime than at night, while the levels of GLP-1 and GIP were lower at night, which may be the reason for the frequent increase of food intake at night, thereby increasing the risk of obesity (18). The gene discussed is GCG; the disease is obesity due to melanocortin 4 receptor deficiency.