Background: Cognitive restraint, a stable disposition to limit food intake, can be assessed by questionnaires, but there is no quantitative, objective measure of its effect.
Objective: The goal was to provide an objective measure of the intake-limiting effects of cognitive restraint by testing meal intake under conditions intended to minimize or accentuate restraint.
Design: Healthy women (n = 41; aged 35 +/- 9 y; body mass index, in kg/m2: 21.3 +/- 1.9) participated in once-weekly laboratory lunch tests under 4 conditions: condition 1, subjects ate alone (baseline); condition 2, subjects ate alone while listening to recorded instructions focusing on the sensory characteristics of the foods (attention); condition 3, subjects ate alone while listening to a recorded detective story (distraction); and condition 4, a group of 4 subjects had lunch together. On all occasions, the same foods were presented and ingested ad libitum. The Three-Factor Eating Questionnaire (TFEQ) was filled out after the series of 4 meals was completed.
Results: Meal size was significantly higher in the distraction condition than at baseline (by 301 +/- 26 kJ; P < 0.001). The difference in energy intake between the baseline and distraction conditions significantly correlated with factor 1 (cognitive restraint) of the TFEQ (r = 0.51, P < 0.01) and with total score (r = 0.32, P < 0.05) but not with disinhibition or hunger. For each additional point on factor 1, meal size increased by 50 kJ under the distraction condition compared with baseline. The group eating condition induced no increase in meal size.
Conclusion: Cognitive restraint exerts a quantifiable limiting effect on intake at meal times and this effect can be offset by cognitive distraction.