Childhood obesity: the genetic-environmental interface

Obesity has a high prevalence in children living in industrialized countrie s. Excess adiposity is the result of a prolonged positive energy balance. B oth genetic and environmental factors are involved. A genetic predispositio n to obesity has been ascertained from, for example, twin studies. Animal m odels of genetic obesity have been used to identify candidate genes, which have, in some cases, also been demonstrated in humans. Genome scanning has highlighted some of the human genes that may be involved. Several environme ntal factors promote an imbalance between nutrient intake and nutrient oxid ation in genetically predisposed children. Fat intake is associated with ad iposity in children. The low thermogenesis induced by fat intake is another potential contributory factor. Oxidative activity in skeletal muscles grea tly influences total energy expenditure as well as fat oxidation rate. Sede ntary behaviour promotes low energy requirements in children. Moreover, low skeletal muscle activity reduces fat oxidation, favouring fat gain. Severa l socio-economic and cultural factors affect the dietary and physical activ ity habits of children. Finally, the enlargement of the fat mass induces co mpensatory metabolic reactions to oppose further fat gain. Further research on the factors responsible for the pathogenesis of obesity is necessary to identify more sensitive targets for the effective prevention and treatment of childhood obesity.