Effects of a Web-based Food Portion Training Program on Food Portion Estimation

Objective: Assess the effects of a prototype computerized food portion tutorial (CFPT). Design: Participants were randomly assigned to estimate portion sizes for selected food items either prior to or following CFPT training (between groups), and those estimating before CFPT training re-estimated portions after training (within groups). Setting: Research offices. Participants: Seventy-six adult participants without dietary restrictions. Intervention: The CFPT is a Web-based food portion training program that displays varied portions of 23 food items with user-controllable reference objects and viewing angles. Main Outcome Measures: Estimated vs. weighed portions of food items selected for a meal. Analysis: Nonparametric tests were performed on estimated vs. weighed portion differences and on accuracy ratios between and within groups. Results: A significant difference was found between conditions, both within and between groups, on the discrepancy between estimated and weighed portions for a number of the food items. Training exposure, however, resulted primarily in a shift from underestimation to overestimation, not more accurate estimation. Implications for Research and Practice: The CFPT produced a significant impact on food portion estimation but appeared to sensitize participants to underestimation errors, leading to overestimation errors. Computerization of food portion training programs holds promise for providing cost-efficient portion estimation training but requires further development and evaluation before being considered for clinical use.