The Effect of a Future-Self Avatar mHealth Intervention on Physical Activity and Food Purchases: The FutureMe Randomized Controlled Trial

Background: Insufficient physical activity and unhealthy diets are contributing to the rise in non-communicable diseases. Preventative mobile health (mHealth) interventions may enable reversing this trend, but present bias might reduce their effectiveness. Future-self avatar interventions have resulted in behavior change in related fields, yet evidence whether such interventions can change health behavior is lacking. Objective: Our primary objectives are to investigate the impact of a future-self avatar mHealth intervention on physical activity and food purchasing behavior, and to examine the feasibility of a novel automated nutrition tracking system. We also aim to understand how this intervention impacts related attitudinal and motivational constructs. Methods: We conducted a 12-week parallel randomized-controlled trial (RCT), followed by semi-structured interviews. German-speaking smartphone users aged ≥18 years living in Switzerland, and using at least one of the two leading Swiss grocery loyalty cards, were recruited for the trial. Data were collected from November 2020 to April 2021. The intervention group received the FutureMe intervention—a physical activity and food purchase tracking mobile phone application that uses a future-self avatar as the primary interface and provides participants with personalized food basket analysis and shopping tips. The control group received a conventional, text- and graphic-based primary interface intervention. We pioneered a novel system to track nutrition leveraging digital receipts from loyalty card data analyzing food purchases in a fully automated way. Data were consolidated in 4-week intervals and non-parametric tests were conducted to test for within- and between-group differences. Results: We recruited 167 participants; 95 eligible participants were randomized into either the intervention (n=42) or control group (n=53). The median age was 44.00 years (IQR 19.00), and the gender ratio was balanced (female 52/95, 55%). Attrition was unexpectedly high with only 30 participants completing the intervention, negatively impacting the statistical power of our study. The FutureMe intervention led to directional, small increases in physical activity (median +242 steps/day) and to directional improvements in the nutritional quality of food purchases (median –1.28 British Food Standards Agency Nutrient Profiling System Dietary Index points) at the end of the intervention. Intrinsic motivation significantly increased (P=.03) in the FutureMe group, but decreased in the control group. Outcome expectancy directionally increased for the FutureMe group, but decreased for the control group. Leveraging loyalty card data to track the nutritional quality of food purchases was found to be a feasible and an accepted fully automated nutrition tracking system. Conclusions: Preventative future-self avatar mHealth interventions promise to encourage improvements in physical activity and food purchasing behavior in healthy population groups. A full-powered RCT is needed to confirm this preliminary evidence and to investigate how future-self avatars might be modified to reduce attrition, overcome present bias, and promote sustainable behavior change.