Abstract Men in the United States have an exceptionally high prevalence of overweight and obesity, i.e., 71.3%, and 42% of men are currently attempting weight loss. However, men are dramatically underrepresented in weight loss programs. Men find conventional weight loss program (i.e., group-based, education and counseling- orientated, dietary/calorie-focused) unappealing because they involve receiving counseling, focus on replacing “masculine” foods (e.g., meat) with “feminine” ones (e.g., salad), and provide minimal personalization or autonomy. As such, attempts have been made to increase recruitment and appeal through targeted recruitment and adaptations to standard weight loss programs. However, these efforts have been disappointing. Mobile applications (mHealth apps) have attractive features, but have low male enrollment and poor efficacy as conventionally delivered. A gamified mHealth program offers the possibility of engaging men and enhancing efficacy given that (1) video gaming is highly appealing to men; (2) gamification features (e.g., digital rewards for attaining “streaks” and milestones, competition) are known enhance enjoyment and motivation and facilitate desired behaviors; and (3) “neurotraining” video games featuring repetitive action mechanics, adaptive difficulty, and feedback can train inhibitory control, a basic brain capacity to inhibit intrinsically-generated approach responses that is strongly linked to body mass and the consumption of high- calorie foods. Inhibitory control training (ICT) games have been successful at reducing consumption of targeted foods/beverages and improving short-term weight loss. For instance, in our preliminary work we demonstrated that a weight loss workshop plus a short, daily ICT produced greater weight loss for individuals with higher- than-average implicit preferences for high-sugar foods, compared to a robust attention control (i.e., the workshop plus a sham training), and we found that adding gamification elements (e.g., story, music, levels) to a rudimentary game produced additional 8-week weight loss for men (4.1% vs 2.5%). This project extends previous work by evaluating the independent effects of gamification and ICT on long-term engagement and outcomes. As such, 243 men with BMI ≥ 25 will be recruited, with 15 participating in usability testing and 228 assigned to a 12-month mHealth weight loss program that prescribes digital self-monitoring and dietary and physical activity targets. Utilizing an efficient 2 x 2 factorial design, participants will be randomized to receive either a standard or fully-gamified program, comprised of a behavior change program featuring team-based competition, and digital reinforcers for attainment of streaks and milestones, and also randomized to receive either sham or active inhibitory control neurotraining. Aims include evaluating the efficacy of gamification and ICTon weight loss, diet and physical activity at 12 months, as well as evaluating hypothesized mediators (engagement and inhibitory control) and moderators (baseline frequency of video game play and implicit preferences for ICT-targeted foods).

Project Narrative Men in the United States have an exceptionally high prevalence of overweight and obesity, but are dramatically underrepresented in weight loss programs because they find them unappealing. This project evaluates engagement in and efficacy of a novel, game-based mobile weight loss program designed to be appealing to men. The program is designed to be especially effective and engaging because it features both gamification features known to enhance enjoyment and motivation and facilitate desired behaviors and neurotraining in basic brain capacities needed to resist impulses to eat tempting foods.