The additive effects of energy density and portion size on energy intake in women

Results from previous experiments have shown that the energy density (kcal/g) of foods significantly affects energy intake. The consumption of higher energy-dense foods is associated with significantly higher energy intakes compared to the consumption of lower energy-dense foods. Studies that examined the effects on food and energy intake of the portion size of foods, independent of their energy density, found that increases in portion size significantly increases intake. The aim of the following study was to determine how the energy density and the portion size of foods interact to affect energy intake in normal-weight and overweight women.; In a within-subjects design, 39 women were served breakfast, lunch and dinner in our laboratory once a week for six weeks. The main entrée at lunch, consumed ad libitum, was formulated in two versions that varied in energy density (1.25 kcal/g and 1.75 kcal/g), each of which was served in three different portion sizes (500, 700, and 900 g) on different test days. The two versions of the main entrée were matched in macronutrient composition and palatability. Breakfast and dinner consisted of standard meals and were consumed ad libitum.; The results of this study showed that there was a main effect of portion size (p < 0.0001) and a main effects of energy density (p < 0.0001) on energy intake. This indicates that the two factors add together to affect caloric intake. Subjects consumed 56% more energy (221 kcal) when served the large portion of the higher energy-dense entrée compared to when served the small portion of the lower energy-dense entrée. Subjects did not compensate for the additional energy intake by eating less at the subsequent meal. In addition, despite substantial differences in energy intake, there were no significant differences in hunger and fullness ratings across conditions.; The results from this experiment indicate that the energy density and the portion size of a food act independently to affect energy intake. Therefore, the combination of large portion sizes of foods with a high energy density may facilitate the overconsumption of energy.