Objective: Examination of the role of macronutrient selection in determining patterns of food intake in obese and non-obese women.
Design: Inventory: food intake diaries of two weekdays and one weekend day; EXPERIMENT randomized.
Setting: Inventory: in daily life.
Experiment: department of Human Biology, University of Limburg.
Subjects: 68 subjects: 34 obese and 34 non-obese, age 20-50 years, selected based on accurate completion of food intake diaries (< 10% underreporting); a sub-sample of 32 (16 obese and 16 non-obese) was assigned to the experiment.
Interventions: An ample choice of food items consisting of mainly one macronutrient each were offered 4 and 6 times per day, with different macronutrient compositions per day, ranging from 1-77 en% fat, 3-45 en% protein, and 19-96 en% carbohydrate.
Results: Selection, namely food choice that differs from random consumption, took place at breakfast in favour of carbohydrate, and at dinner in favour of fat. Habituation, namely a decreased response on the same stimulus, occurred after the fourth exposure to a single macronutrient buffet. For protein this was expressed as a significantly increased satiety score per kJ ingested; for fat as a significant drop in hedonic value; for carbohydrate as a significantly increased desire for a different taste, all (P < 0.05). Compensation, i.e. a correction afterwards for an earlier unusual macronutrient composition, resulting in a close to usual macronutrient composition of 24 h food intake, occurred at dinner, for a previous unusually low fat and high carbohydrate intake.
Conclusions: A pattern of macronutrient intake was achieved by selection and compensation. Habituation occurred at the fourth exposure of a single macronutrient.