Abstract: Background: The increasing burden of non-communicable diseases (NCDs), which are prevalent in low and middle income countries (LMICs), is largely attributed to modifiable behavioural risk factors such as poor/unhealthy diets and insufficient physical activity (PA). The adolescent stage–recently defined as 10-24 years of age–is an important formative phase of life and offers an opportunity to reduce NCD risk across the life course and for future generations.

Objective: To describe a protocol for a study utilising a convergent mixed methods design to explore exposures in the household, neighbourhood, school, and the journey from home to school, that may influence diet and PA behaviours in adolescents from LMICs.

Methods: Male and female adolescents (n ≥150) aged between 13-24 years will be recruited from purposively selected high schools or households in project site countries to ensure socioeconomic diversity of perspectives and experiences at individual, home and neighbourhood levels. The project will be conducted in five sites in four countries: Kenya, Cameroon, Jamaica and South Africa (Cape Town and Johannesburg). Data on anthropometric measures, food intake and PA knowledge and behaviour will be collected using validated self-report questionnaires and objective measurement in a sub-sample. Additionally, a small number of learners (n=30-45) from each site will be purposively selected as citizen scientists to capture data (photos, audio notes, text, and geolocations) on their “lived experiences” in relation to food and PA in their homes, the journey to and from school, and school and neighbourhood environments, using a mobile application (EpiCollect5). In-depth interviews will be conducted with the citizen scientists and their caregivers to explore household experiences and determinants of food intake and foodways, as well as PA of household members.

Results: The primary objective and outcome of the study described by this protocol paper is to determine the barriers and facilitators (levers) of healthy diet and PA of adolescents in their household, neighbourhood and school environments, and during the journey from home to school. It is also to compare the similarities and differences of these levers between settings and across socio-ecological domains. Secondary outcomes include to explore the potential of a participatory citizen science approach to build agency among adolescents to inform future policy to promote healthy diet and PA. Data collection is on-going and analysis will follow once data collection is complete.

Conclusion: This project protocol contributes to research that focuses on adolescents and the socio-ecological determinants of food intake and PA in LMIC settings. It includes innovative methodologies to interrogate and map the contexts of these determinants and will generate much needed data to understand the multi-level system of factors that can be leveraged through upstream and downstream strategies and interventions to improve health outcomes.