Short-term effects of macronutrient preloads on appetite and energy intake in lean women.

This study investigated the relative satiating hierarchy of the four energy-providing macronutrients (fat, carbohydrate (CHO), protein, and alcohol) in lean women. On four separate occasions, the composition of an iso-energetic lunch preload was manipulated in 12 lean (BMI < 25 kg/m2) women. The four treatments comprised a 1-MJ baseline meal and drink (40% fat, 48% CHO, 12% protein) to which was covertly added: 1) + 1MJ protein; 2) + 1MJ alcohol; 3) + 1MJ CHO; and 4) + 1MJ fat. Prior to and at 30-min intervals, subjects completed 100-mm visual analogue scales rating subjective hunger and satiety. Ninety min following the preload, an ad lib. lunch meal was given (40% fat, 48% CHO, and 12% protein) and energy intake (EI) measured. Energy intake at the lunch meal was 2195 (880, SD) kJ, 2772 (1191, SD) kJ, 2502 (681, SD), kJ and 2558 (1050, SD) kJ for the protein, alcohol, CHO, and fat preloads, respectively. There was no significant difference between the pleasantness of the preloads (p > 0.05). Macronutrient composition had a significant effect on short-term hunger (F = 3.19; p < 0.05), subjects being less hungry after the protein preload. Subjects also had a lower energy intake after the protein preload (F = 3.11; p < 0.05). We conclude that only protein has a differential short-term satiating effect when incorporated iso-energetically and at a similar energy density into the diet.