Unravelling the Effects of the Healthy Primary School of the Future: For Whom and Where Is It Effective?

The 'Healthy Primary School of the Future' (HPSF) aims to integrate health and well-being within the whole school system. This study examined the two-year effects of HPSF on children's dietary and physical activity (PA) behaviours at school and at home and investigated whether child characteristics or the home context moderated these effects. This study (n = 1676 children) has a quasi-experimental design with four intervention schools, i.e., two full HPSF (focus: nutrition and PA), two partial HPSF (focus: PA), and four control schools. Measurements consisted of accelerometry (Actigraph GT3X+) and questionnaires. Favourable effects on children's dietary and PA behaviours at school were found in the full HPSF; in the partial HPSF, only on PA behaviours. Children in the full HPSF did not compensate at home for the improved health behaviours at school, while in the partial HPSF, the children became less active at home. In both the full and partial HPSF, less favourable effects at school were found for younger children. At home, less favourable effects were found for children with a lower socioeconomic status. Overall, the effect of the full HPSF on children's dietary and PA behaviours was larger and more equally beneficial for all children than that of the partial HPSF.