Genetic influences on human energy expenditure and substrate utilization.

Understanding the genetic factors of obesity requires consideration of the genetic basis of the underlying etiological factors including energy expenditure and substrate utilization. Genetic susceptibility studies suggest that altered energy expenditure and/or preferential substrate utilization are likely to be involved in the etiology of obesity. Twin and family studies suggest that there is a strongly heritable component to resting energy expenditure, substrate utilization, and the thermic response to feeding. Physical activity energy expenditure has been less well studied; new data are presented in young sib pairs that suggest moderate heritability of nonresting energy expenditure. Only a few candidate gene studies have been performed to examine the role of basic proteins involved in energy expenditure (the sodium-potassium ATPase and the uncoupling protein) or substrate utilization (fatty acid binding protein). The lack of information in this area warrants further investigation into genetic aspects of energy and substrate metabolism.