The aim of the current study is to describe the effectiveness of a school-based intervention when delivered by a non-nutrition specialist (trained schoolteachers) as compared to an expert in nutrition.
Two trials of the same school-based intervention using the same intervention package were delivered, one by nutritionists and another by trained schoolteachers. The intervention focused mainly on dietary behaviours, as well as physical activity. In both trials, purposively selected schools were randomized to intervention or control groups; students (aged 9–11 years) in both groups were compared at post-test on knowledge and self-efficacy scores, as well as dietary and physical activity behaviours, controlling for their baseline status on the various measures. All analyses accounted for clustering at the school level.
In both trials, a statistically significantly greater improvement was observed for both the knowledge and self-efficacy scores in intervention vs. school students. When the programme was delivered by trained schoolteachers, frequency of breakfast intake was increased, crisps consumption was reduced, but no change in fruit and vegetable consumption was observed (latter increased when delivered by nutrition professionals only). Physical activity did not improve in both trials.
Trained schoolteachers can have a positive impact on students’ dietary behaviours with the appropriate training to ensure they are equipped with the right information, skills, and resources to deliver the programme with the highest fidelity.
Summary of Physical Activity results
Students’ physical activity did not change or improve in both interventions, which may be explained by external factors such as limited accessibility to extra-curricular activities, be it due to budget constraints, homework overload or the lack of safe and free places for spontaneous physical activity or play, all of which were reported as barriers to improved frequency of after-school sports in previously held focus group discussions as part of the process evaluation of the pilot study 
Other reviews have shown that the null effect of school-based physical activity interventions on children’s moderate to vigorous physical activity may be due to interventions not reaching target populations as intended. Authors concluded that further assessments of intervention fidelity are required . Increasing the number of physical education sessions per week, at school, may be a more appropriate goal for schools in low to middle-income countries.
Other researchers have noted that change in physical activity may necessitate more targeted individual behavioural interventions which was not the case in our study .We acknowledge that our study has limitations. Dietary behaviors and physical activity were self-reported and thus were subjectively assessed, and are prone to reporting error. Another limitation, is the reduced number of physical education sessions and the absence of sports experts in both trials, which may have affected the improvement in students’ physical activity levels as nutritionists are probably not best suited to deliver active living components.
While this study is the first to describe the findings of two trials delivering the same intervention package, it did not directly assess the difference in the impact of the intervention when delivered by the nutritionists or the schoolteachers. Finally, the baseline dietary and physical activity behaviours, as well as knowledge and self-efficacy scores were comparable between students who were lost to follow-up and those with complete data, within and across intervention and control groups; thus, it is unlikely that any differential misclassification bias was introduced.