Youth Engagement for Better Outcomes – Social Networks, Physical Activity and Nutrition (YEBO-SPAN): Protocol for “Future-Proofing” South African Adolescents (Preprint)

<sec> <title>BACKGROUND</title> Adolescence represents a critical period where health behaviours emerge that track into adulthood. In South Africa, 22.4% of girls and 10.2% of boys aged 10-14 years are overweight or obese, with only 40% meeting physical activity recommendations. </sec> <sec> <title>OBJECTIVE</title> This protocol describes an innovative mixed-methods intervention leveraging participatory citizen science and human-centred design to engage South African adolescents in addressing barriers to healthy lifestyle behaviours. </sec> <sec> <title>METHODS</title> The YEBO-SPAN study employs a citizen science "by the people" approach based on the Our Voice global citizen science research method, while also integrating human-centred design principles. Eight high schools in Cape Town were invited to participate in the study, with a focus on Grade 9 learners (14-15 years) who have self-select as Citizen Scientist Explorers (completing self-assessment surveys on lifestyle behaviours and social networks) or Discoverers (engaging in the four-step Our Voice process: Discover, Discuss, Activate, Change). The intervention aligns with the Western Cape Education Department's Life Orientation curriculum. Data collection includes validated instruments for physical activity, dietary patterns, sleep quality, mental wellbeing, and egocentric social network analysis. Citizen scientists used mobile technology for geo-tagged photographic and audio-narrative environmental assessments, followed by participatory workshops to analyse findings, prioritize intervention targets, and develop advocacy strategies. Ripple effects mapping evaluates intended and unintended outcomes. </sec> <sec> <title>RESULTS</title> The intervention started in August 2024 and will conclude in mid-2026. Published study results are expected in early 2026. </sec> <sec> <title>CONCLUSIONS</title> This protocol represents the first integration of citizen science and human-centred design in South African schools, generating actionable insights into how environments shape adolescent health behaviours. By embedding the multi-modal procedures within existing curriculum structures and emphasizing youth-led advocacy, the study creates pathways for systems-level impact and horizontal scaling. The approach addresses critical gaps in theory-based, co-created interventions for adolescent health in low- and middle-income countries while centering voices of those most affected by health inequities. This framework offers a replicable model for youth-engaged health promotion research globally. </sec>