Construal beliefs moderate the usability and effectiveness of a novel healthy eating mobile app

Abstract Reduced self-control is a strong predictor of overeating and obesity. Priming a high construal level mind-set has been shown to enhance self-control and reduce snack consumption in the lab but the long-term and real-world effects are not known. The use of digital technology is an efficient way to deliver priming cues in real-world settings. Many mobile apps claim to support healthy eating but few are grounded in psychological theories of self-control. The aim of this study was to test the feasibility and effectiveness of a novel, construal-theory-based mobile app to promote self-control and healthy eating. In an exploratory analysis, the moderating influence of user characteristics was also examined. Using an iterative process involving users at every stage of the process, a prototype mobile app was developed. The final version included a high construal, self-control priming task, sent personalised reminder cues before each eating occasion, provided a just-in time ‘crave-buster’ for unanticipated eating opportunities and an optional food log. In a longitudinal trial the app was used over an eight-week period (N=71; 51 females; M (SD) Age = 33.34 (11.68) years; M (SD) BMI = 26.22 (4.94)) with pre-post measures of weight, percent body fat and dietary intake. The app received high usability ratings on the System Usability Scale (M=76.55; SD=11.35), however food intake, per cent body fat and weight pre- and post- app use showed no significant change (p>.05). Exploratory analyses showed that baseline construal belief moderated the extent to which engagement with the app predicted dietary changes (p