Behavioral genetics of food intake regulation in free-living humans

It has been established that the genes influence body size. Recently, it has become clear that food intake is also influenced by heredity. Surprisingly, the genetic effect on intake was found to occur independent of body size. Taking height and body weight into consideration, strong influences of heredity were found on the total amounts of food energy, macronutrients, and fluids ingested. Also, genetic influences were found related to the microstructure of intake, affecting the number, timing, and composition of meals. Since overall intake is determined by the size and frequency of meals, this was not surprising. However, these heritable factors were shown to influence meal size and frequency even when overall daily intake was considered in the model. Recently, we have shown that there are even heritable factors that influence the choice of the environmental conditions at the meals; the time, degree of hunger, stomach fullness, and the number and type of people at the meal. Also the degree to which these conditions affect intake appears to be heritable. These findings suggest that there are important heritable factors that influence body size, overall daily intake independent of body size, meal intake independent of overall daily intake, and the selection of and responsivity to the environmental conditions surrounding eating.