Heredity influences the dietary energy density of free-living humans.

Dietary energy density has been shown to have large effects on short-term food intake. Little is known, however, about its origins. We investigated the influence of heredity, shared (familial) environment, and individual environment on dietary energy density and its relationship to food intake with 110 identical and 102 fraternal same-sex and 53 fraternal mixed gender adult twin pairs who were paid to maintain 7-day food intake diaries. From the diary reports, the total and meal intakes of food energy, the amounts of the macronutrients ingested, and dietary energy density were estimated. Linear structural modeling was applied to investigate the nature and degree of genetic and environmental influences. The analysis revealed significant genetic and individual environmental, but not shared (familial) environmental, influences on the dietary densities of the reported diets. But, there was no genetic or familial influences on the responsiveness of the individual to dietary density. Dietary energy density appears to be another component in a package of genetically determined physiological, sociocultural, and psychological processes that influence the regulation of energy balance.