Feasibility of a theory-based multicomponent intervention to improve diet and activity behaviours among primary school children: a pilot study

BACKGROUND: School-based multicomponent interventions have shown promise in improving children's lifestyle behaviours, but evidence on their feasibility in Asia remains limited. The Promoting hEalthy Diet and Active Lifestyle intervention was developed for primary school children (ages 10-11 years) in Singapore to improve diet and activity behaviours (fruit and vegetable intakes, moderate-to-vigorous physical activity (MVPA) time, and recreational screen time), through lessons, take-home activities, parental engagement, and environmental modifications. This pilot study evaluated six feasibility dimensions: recruitment; data collection; implementation fidelity; practicality; social validity; and potential effectiveness, particularly of our theory-based approach, which focuses on ideations and their impact on behaviour. METHODS: A concurrent mixed-methods study design was employed in two public co-educational schools. This involved a pre-post survey of students' self-reported behaviours (n = 139) and to generate healthy eating (HE) and physically active (PA) ideation scores, focus group discussions with students (n = 20) and teachers (n = 11), teacher-reported feedback forms (n = 13 classes), short interviews with canteen vendors (n = 11), and observation to evaluate environment modifications. RESULTS: Student survey completion rate was low (57%) due to insufficient time, although lessons were well-liked by students and teachers, with high student attendance (97%). Teachers delivered 83% of the planned activities, with time constraints being a barrier. There were no significant changes in the behaviours or HE ideation scores, although PA ideation scores improved (+ 0.3, 95% CI: 0.03-0.6) due to increased knowledge scores (+ 0.5, 95% CI: 0.4-0.7). While this increase in knowledge did not result in behavioural changes, the association between ideation scores and behaviours aligned with theoretical expectations. Higher HE ideation scores correlated with greater fruit and vegetable intake, while higher PA ideation scores were associated with more MVPA and less recreational screen time. CONCLUSION: Poor fidelity in take-home activities and parental engagement, along with students' inertia and perceived lack of need for change, explained the absence of significant behavioural change. The study identified key conditions for better implementation, including stronger stakeholder buy-in, flexible lesson delivery, and digital data tracking. It highlighted the complexity of behaviour change in Singapore primary schools, emphasising the need for long-term, tailored interventions. TRIAL REGISTRATION: ISRCTN16114046. Registered 16/10/2022, prospectively.