The effect of a dietary preload on estimation of usual food portion size by photograph in female volunteers

Background The aim of this study was to investigate whether a subject's level of satiety influences perception of their usual portion size. Methods A total of 62 school children were recruited for the pilot study. Half of the group assessed food photographs for their usual portion size before lunch, and half after lunch. For the main study, 55 female students were recruited to test within-subject variation in perception of usual portion size before and after consuming a preload. Results Significant differences in perception of portion size were found for four of the six foods used. Conclusion Some subjects' perception of their usual portion size was influenced by their level of satiety. Further study is needed to investigate this using a wider variety of food photographs and an alternative preload.