Genetic influences on daily intake and meal patterns of humans.

The heritability of nutrient intake was investigated with 109 identical and 86 fraternal adult twin pairs who were paid to maintain 7-day food intake diaries. Both classical analysis of heritability and linear structural modeling revealed significant additive genetic influences on body size, height and weight, and body fatness (body-mass index). Significant heritabilities were also found for the amount of food energy ingested daily, as well as its macronutrient, alcohol, and water content. Linear structural modeling analysis showed that 65% of the variance in energy intake was attributable to heredity. In addition, the pattern of intake, meal frequency, size, and meal macronutrient, alcohol, and water composition, were also found to have strong heritabilities. Linear structural modeling indicated that 44% of the variance in meal frequency and 65% of the variance in meal size was attributable to heredity. However, shared, familial environment had no significant impact on the levels or pattern of intake in adulthood. These results indicate that not only body size but also the pattern and amounts of nutrients ingested by humans in natural environments are strongly influenced by the immediate environment and heredity, but not at all by the familial environment.