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

Abstract

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.

Keywords: awareness; intervention; nutrition education; online; portion size.