Plate-clearing tendencies and portion size are independently associated with main meal food intake in women: A laboratory study

Background: Larger portion sizes of food promote increased food intake, although the mechanisms explaining the portion size effect are unclear. In the present study we examined whether the tendency to clear ones plate when eating is associated with greater food intake in response to larger portion size. Method: We recruited female participants who were either self-reported habitual plate clearers (N = 48) or non-plate clearers (N = 41) into a laboratory study. In a between-subjects design, participants were served either a 'normal' (500 g) or 'large' (1000 g) portion of pasta for lunch and ate as much as they desired. Results: There was no significant interaction found between portion size and plate-clearing tendencies; portion size had a similar sized effect on food intake in both plate clearers and non-plate clearers. A significant main effect of portion size was found, whereby participants consumed significantly more when served the large versus the normal portion (100.55 g difference, p < .001, eta(2)(p) = 0.16). There was also a significant main effect of plate clearing; participants with a tendency to clear their plate when eating consumed significantly more than non-plate clearers (68.21 g difference, p = .006, eta(2)(p) = 0.08). Conclusions: The tendency to clear one's plate when eating was associated with increased food intake during a lunchtime meal. Increasing the portion size of the lunchtime meal increased food intake, although the tendency for a larger portion size to increase food intake was observed irrespective of participant plate-clearing tendencies.