Psychological factors associated with ratings of portion size: relevance to the risk profile for obesity.

The ability to assess accurately the relative size of food portions is highly variable in the population. This study was designed to identify salient individual differences that correlate with this variation since estimation errors are seen as a barrier to the control of food intake and a detriment to many obesity treatment strategies. Healthy weight and obese adult women were assessed on a self-report measure of food amount ratings. We predicted that a high sensitivity to reward, symptoms of binge eating, and a preference for fat foods would relate positive to scores on this rating scale, and that weight status might moderate these relationships. As expected, a preference for high-fat food was associated with the tendency to under-estimate portion sizes. A significant interaction between weight status and reward sensitivity indicated that high values on the latter were correlated with ratings reflecting under-estimation of food amounts--but only among obese individuals. This study identified important factors that may influence estimation biases in food amount ratings-information of direct relevance to research and treatment protocols that use food diaries and focus on efforts to normalize eating behaviours.