The FTO (Fat mass and obesity-associated) gene encodes a protein that is a demethylase, playing a crucial role in energy metabolism and body weight regulation. FTO is primarily expressed in the brain, muscles, and adipose tissue, with its expression in the hypothalamus particularly regulating appetite and energy expenditure. By affecting the methylation levels of mRNA, FTO modulates gene expression and participates in signaling pathways related to lipid metabolism and insulin sensitivity. Variations in the FTO gene are closely associated with an increased risk of obesity, especially affecting the regulation of appetite and energy intake. Furthermore, mutations in the FTO gene are also linked to susceptibility to type 2 diabetes, cardiovascular diseases, and other metabolic disorders.