Portion size measurement aids (PSMAs) are tools that facilitate the estimation of food servings. The objectives of this study are to determine (a) if food portion size estimation accuracy differs when using a two dimensional (2D) PSMA (actual-size photos called Portion Size Cards) compared to a 3D PSMA (Portion Size Kit) and (b) whether differences exist in the short-term usefulness of and satisfaction with these PSMAs in a sample of parents of overweight children and youth. We hypothesize that the group that receives the 3D PSMAs will be more accurate in food portion size estimation and will be more satisfied with the tool compared to the group that receives the 2D PSMAs.

Forty primary caregivers of overweight children and youth attending the Pediatric Centre for Weight and Health (Edmonton, AB) will be recruited. Participants will be randomly assigned to one of the two groups (2D PSMAs versus 3D PSMAs). After a brief explanation of the respective tool, participants will estimate the volumes of pre-measured rubber food portion models on a test plate. Participants will then be given the 2D or 3D PSMAs to take home with them to use in the real-world. After 2-4 weeks, participants will be telephoned by the research team to complete a brief survey to evaluate their usefulness of and satisfaction with the 2D or 3D PSMAs at home.