Smart-phone obesity prevention trial for adolescent boys in low-income communities: the ATLAS RCT.

OBJECTIVE: The goal of this study was to evaluate the impact of the Active Teen Leaders Avoiding Screen-time (ATLAS) intervention for adolescent boys, an obesity prevention intervention using smartphone technology. METHODS: ATLAS was a cluster randomized controlled trial conducted in 14 secondary schools in low-income communities in New South Wales, Australia. Participants were 361 adolescent boys (aged 12-14 years) considered at risk of obesity. The 20-week intervention was guided by self-determination theory and social cognitive theory and involved: teacher professional development, provision of fitness equipment to schools, face-to-face physical activity sessions, lunchtime student mentoring sessions, researcher-led seminars, a smartphone application and Web site, and parental strategies for reducing screen-time. Outcome measures included BMI and waist circumference, percent body fat, physical activity (accelerometers), screen-time, sugar-sweetened beverage intake, muscular fitness, and resistance training skill competency. RESULTS: Overall, there were no significant intervention effects for BMI, waist circumference, percent body fat, or physical activity. Significant intervention effects were found for screen-time (mean ± SE: -30 ± 10.08 min/d; P = .03), sugar-sweetened beverage consumption (mean: -0.6 ± 0.26 glass/d; P = .01), muscular fitness (mean: 0.9 ± 0.49 repetition; P = .04), and resistance training skills (mean: 5.7 ± 0.67 units; P < .001). CONCLUSIONS: This school-based intervention targeting low-income adolescent boys did not result in significant effects on body composition, perhaps due to an insufficient activity dose. However, the intervention was successful in improving muscular fitness, movement skills, and key weight-related behaviors.