Genetics of Energy Expenditure in Humans

Reduced energy expenditure for a given energy intake level causes positive energy balance and eventually may lead to excess body weight and obesity. Two kinds of genetic effects are considered in this chapter. The first one is additive genetic effect, or the so-called heritability, and the second one is the genotype-environment interaction effect. Resting Metabolic Rate is a complex phenotype associated with the metabolic rates of all tissues and organs of the body measured in the basal state after an overnight fast. Although the mechanisms linking high fat consumption to increased body fat stores remain to be elucidated, inter-individual differences in substrate oxidation, particularly lipid oxidation, are likely to be involved. The thermic effect of food is the integrated increase of energy expenditure after food ingestion. Negative or positive energy balance sustained for a long period influences energy expenditure. The studies reviewed here suggest that inter-individual differences observed in various energy expenditure components are partly determined by the genotype.