Effects of a high-protein meal (meat) and a high-carbohydrate meal (vegetarian) on satiety measured by automated computerized monitoring of subsequent food intake, motivation to eat and food preferences.

We have examined the effects on satiety of equicaloric meals with different protein and carbohydrate content. Twenty normal weight healthy women were served cooked lunch meals made of commonly used natural food items with either a high-protein (43 energy %) (a meat casserole) or a high-carbohydrate (69 energy %) (a vegetarian casserole) content in a counterbalanced repeated measures design. The subsequent ad libitum evening meal intake (4 h after lunch) was measured by a 'universal eating monitor' and subjective feelings of motivation to eat and food preferences were assessed repeatedly. At the subsequent evening meal subjects ate 12 per cent less (P less than 0.05) after the high-protein meal compared to the high-carbohydrate meal. There was no difference in motivation to eat between meals. This could partly be explained by a difference in palatability between the meals. The food-preference lists showed that before lunch there was relative preference for high-protein foods in favour of high-carbohydrate foods. After lunch either meal produced instead a relative 'aversion' for high-protein foods. This 'aversion' was greater after the high-protein lunch meal than after the high-carbohydrate lunch meal.