A hierarchy of unhealthy food promotion effects: identifying methodological approaches and knowledge gaps.

We assessed the evidence for a conceptual "hierarchy of effects" of marketing, to guide understanding of the relationship between children's exposure to unhealthy food marketing and poor diets and overweight, and drive the research agenda. We reviewed studies assessing the impact of food promotions on children from MEDLINE, Web of Science, ABI Inform, World Health Organization library database, and The Gray Literature Report. We included articles published in English from 2009 to 2013, with earlier articles from a 2009 systematic review. We grouped articles by outcome of exposure and assessed outcomes within a framework depicting a hierarchy of effects of marketing exposures. Evidence supports a logical sequence of effects linking food promotions to individual-level weight outcomes. Future studies should demonstrate the sustained effects of marketing exposure, and exploit variations in exposures to assess differences in outcomes longitudinally.