Energy density of foods affects energy intake across multiple levels of fat content in lean and obese women

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Abstract
Background: The results of previous studies indicated that energy density, independent of fat content, influences energy intake. In most studies, however, both fat content and energy density were lower than in typical American diets. Objective: We examined the influence of energy density on intake when fat content was above, below, or similar to the amount of fat typically consumed and when energy density was closer to that of American diets. Design: Lean (n = 19) and obese (n = 17) women consumed all meals daily in our laboratory during 6 experimental sessions. The main entrées, consumed ad libitum, were formulated to vary in fat content (25%, 35%, and 45% of energy) and energy density (5.23 kJ/g, or low energy density, and 7.32 kJ/g, or high energy density) but to have similar palatability. Results: Energy density influenced energy intake across all fat contents in both lean and obese women (P < 0.0001). Women consumed less energy in the low (7531 kJ) than in the high (9414 kJ) energy density condition. Despite this 20% lower energy intake, there were only small differences in hunger (7%) and fullness (5%). Women consumed a similar volume, but not weight, of food daily across conditions. Differences in intake by weight, but not volume, occurred because for some versions of manipulated foods, weight and volume were not directly proportional. Conclusions: Energy density affected energy intake across different fat contents and at levels of energy density comparable with those in typical diets. Furthermore, our findings suggest that cues related to the amount of food consumed have a greater influence on short-term intake than does the amount of energy consumed.