Excess weight and obesity are the most important risk factors for common chronic diseases such as type 2 diabetes, heart diseases and fatty liver disease. Obesity can also lead to health problems such as sleep apnea syndrome, joint disorders, gallstones, infertility, and may increase the risk of cancer. Although the most important cause of obesity is nutrition and lifestyle, there are also well-defined genetic risk factors. Some variants in the FTO, MC4R, LEP and LEPR genes are associated with weight gain and obesity risk. However, these genetic risks can be corrected with appropriate epigenetic interventions.

The most important genetic risk factor associated with obesity is polymorphisms in the FTO gene. Each risk allele in this gene was found to be associated with a 1 unit increase in body mass index. The MC4R gene plays an important role in energy balance and appetite control. Some variants of the MC4R gene may increase the risk of obesity. The LEP gene encodes the hormone leptin. Leptin is important in appetite control and regulation of energy expenditure. Variants in the LEP gene, which encodes the hormone leptin, and the LEPR gene, which encodes the receptor to which leptin binds, may contribute to leptin resistance and obesity risk.