Implementation evaluation of school-based obesity prevention programmes in youth; how, what and why?

In an ideal world, one combats public health problems with theory- and evidence-based programmes. In the real world, evidence-based programmes are often lacking and programmes that are developed and implemented are mainly practice-based. Furthermore, if evidence-based programs are available, these are often not implemented as intended, making the effectiveness in real life settings often much lower than ideal.
Three important generic implementation research questions in the context of programme evaluation are: (i) how to promote implementation as intended; (ii) what happens during implementation; and (iii) why did my programme (not) work? In an invited commentary just published in the journal Public Health Nutrition we -with soon-to-be Dr. Femke van Nassau as first author- discuss
these three questions, enriched by our experiences with the school-based obesity prevention programme DOiT(Dutch Obesity Intervention in Teenagers).