Smartphone applications have arisen to be an important asset in today’s healthcare industry. Many consider them to be effective tools to intervene behavior change by real-time delivery and personalized settings and preferences. Many of these apps also connect users, which may exert social influence on users by social comparison, social support and accountability. However, the efficacy of health behavior change apps is limited by the fact that they seldom engage social processes systematically to fit the needs and preferences of individual users (1). Optimization of these apps is thus imminent.