Genetic contributors to obesity.

Genetic and environmental factors interact to regulate body weight. Overall, the heritability of obesity is estimated at 40% to 70%. More than 244 genes have been found to strongly affect adiposity when overexpressed or deleted in mice. These genes can be considered in four broad categories: regulation of food intake by molecular signalling in the hypothalamus and hindbrain by signals originating in adipose tissue, gut and other organs; regulation of adipocyte differentiation and fat storage; regulation of spontaneous exercise activity; and effect on basal and postprandial thermogenesis. Rare variants in the coding sequences of major candidate genes account for an obese phenotype in 5% to 10% of individuals.