Objectives: To evaluate energy expenditure after three isoenergetic meals of different nutrient composition and to establish the relationship between the thermic effect of food (TEF), subsequent energy intake from a test meal and satiety sensations related to consumption.

Design: The study employed a repeated measures design. Ten subjects received, in a randomized order, three meals of 2331+/-36 kJ (557+/-9 kcal). About 68% of energy from protein in the high protein meal (HP), 69% from carbohydrate in the high carbohydrate meal (HC) and 70% from fat in the high fat meal (HF).

Setting: The experiments were performed at the University of Milan.

Subjects: Ten normal body-weight healthy women.

Methods: Energy expenditure was measured by indirect calorimetric measurements, using an open-circuit ventilated-hood system; intake was assessed 7h later by weighing the food consumed from a test meal and satiety sensations were rated by means of a satiety rating questionnaire.

Results: TEF was 261+/-59, 92+/-67 and 97+/-71 kJ over 7 h after the HP, HC and HF meals, respectively. The HP meal was the most thermogenic (P < 0.001) and it determined the highest sensation of fullness (P=0.002). There were no differences in the sensations and thermic effect between fat and carbohydrate meals. A significant relationship linked TEF to fullness sensation (r=0.41, P=0.025). Energy intake from the test meal was comparable after HP, HC and HF meals.

Conclusions: Our results suggest that TEF contributes to the satiating power of foods.