The development and evaluation of an Internet-based intervention to increase awareness about food portion sizes: a randomized, controlled trial.

OBJECTIVE To develop a Web-based tool (PortionSize@warenessTool) and to evaluate its effectiveness in increasing awareness of reference serving sizes and factors that may contribute to overeating in response to large portion sizes. METHODS A randomized, controlled trial (intervention, n = 167; control, n = 143) was conducted. The authors measured awareness of reference serving size and overeating triggers from larger portions by an online questionnaire, assessed at baseline and 1 week later. Exposure dose reflected online activity (eg, number of Web pages viewed). Process evaluation data were collected within the intervention group. RESULTS The intervention group demonstrated significantly higher awareness of reference serving sizes (η(2) = .062; P < .001) and overeating triggers from larger portions (η(2) = .061; P < .001) at posttest. Also, the authors observed a dose-dependent effect that led to improved awareness. CONCLUSIONS AND IMPLICATIONS The PortionSize@warenessTool constitutes a promising tool to improve portion size awareness.