Challenge to go: Systematic development of a theory-based and target group-adapted mobile app intervention to improve eating habits of adolescents and young adults.

BACKGROUND: Due to the widespread use of smartphones, dietary mobile apps are promising tools for preventing diet-related non-communicable diseases early in life. But, most of currently available nutrition apps lack scientific evaluation and user acceptance.

OBJECTIVE: The objective of the present study was the systematic design of a theory-driven and target group-adapted dietary mobile app concept to promote healthy eating habits with a focus on drinking habits as well as consumption of fruits and vegetables in adolescents and young adults, especially in deprived life situations.

METHODS: The design process was guided by the behaviour change wheel (BCW). The development process consisted of three stages. In stage 1, the target behavior was specified, and facilitators and barriers were identified. Furthermore, important insights into target group interests, needs and values in the field of nutrition and apps were revealed. To this end, two empirical studies were conducted with the target group. In stage 2, results of stage 1 were translated into behavior change techniques (BCTs) and finally into app functionalities and features. Consequently, in stage 3, the concept was evaluated and optimized through expert interviews.

RESULTS: Facilitators and barriers for achieving the target behavior were psychological capabilities (e.g. self-efficacy), reflective motivation (e.g. fitness), automatic motivation, social support, and physical opportunity (e.g. time). Target group interests, needs and values in the field of nutrition were translated into target group preferences for app usage, e.g. low usage effort, visual feedback or recipes. Education, training, incentives, persuasion, and enablement were identified as relevant interventions functions. Together with the target group preferences, these were translated via 14 BCTs, such as rewards, graded tasks or self-monitoring, into the app concept Challenge to go (C2go). The expert evaluation suggested changes of some app features for improving adherence, positive health effects and technical feasibility. The C2go concept consists of three worlds: (i) drinking, (ii) vegetable, and (iii) fruit world. In each world, the users are faced with challenges including feedbacks and a quiz. Tips were developed based on the health action process approach and help users to gain challenges and thereby achieve the target behavior. Challenges can be played alone or against someone in the community. Due to different activities, points can be collected, and levels can be achieved. Collected points open access to an infothek, where users can choose content that interest them. An avatar guides user through the app.

CONCLUSIONS: C2go targets adolescents and young adults and aims to improve their fruit and vegetable consumption as well as drinking habits. It is a theory-driven and target group-adapted dietary mobile intervention concept that uses gamification and was systematically developed using the BCW.