RESUMEN
BACKGROUND: New Zealand rates of obesity and overweight have increased since the 1980s, particularly among indigenous Maori people, Pacific people and those living in areas of high deprivation. New Zealand's response to the obesity epidemic has been The Healthy Eating-Healthy Action: Oranga Kai - Oranga Pumau (HEHA) Strategy ('the Strategy'), launched in 2003. Because the HEHA Strategy explicitly recognises the importance of evaluation and the need to create an evidence base to support future initiatives, the Ministry of Health has commissioned a Consortium of researchers to evaluate the Strategy as a whole. METHODS: This paper discusses the Consortium's approach to evaluating the HEHA Strategy. It includes an outline of the conceptual framework underpinning the evaluation, and describes the critical components of the evaluation which are: judging to what extent stakeholders were engaged in the process of the strategy implementation and to what extent their feedback was incorporated in to future iterations of the Strategy (continuous improvement), to what extent the programmes, policies, and initiatives implemented span the target populations and priority areas, whether there have been any population changes in nutrition and/or physical activity outcomes or behaviours relating to those outcomes, and to what extent HEHA Strategy and spending can be considered value for money. DISCUSSION: This paper outlines our approach to evaluating a complex national health promotion strategy. Not only does the Evaluation have the potential to identify interventions that could be adopted internationally, but also the development of the Evaluation design can inform other complex evaluations.