Appendix A: Project Scope and Methods

The objective of the project was to understand how evidence on what works to shift people towards healthy sustainable diets can be better translated for, and adopted by, food policymakers and practitioners.  The remit of the project was to focus on the retail-consumption end of the food chain, including retail, catering and eating, while acknowledging that the earlier activities in the chain - in particular, manufacturing, but also farming - influence diets, and have a role to play in achieving a healthy sustainable diet shift. The research for the project was conducted between August 2021 and January 2022. Appendix C addresses definitions of a healthy sustainable diet. For this project, a healthy sustainable diet is understood as a pattern of consumption behaviour that prioritises both human (social, cultural and nutritional safety, sufficiency and adequacy) and planetary (considering planetary boundaries) health ^{(footnote 1)}.  

The Guiding Principles were developed by a team of researchers from the University of York and University of Hertfordshire, through a co-creative process with evidence generators, policymakers and practitioners. The Guiding Principles are based on a rapid review of literature on evidence-use and primary research. The literature review addressed how the evidence process works, who is involved, the needs of different evidence users, including policymakers and practitioners, and the barriers to and enablers of evidence-use. The primary qualitative research was used to understand the specific needs of policymakers and practitioners in the field of diet shift. This included elite interviews, workshops, follow-up interviews and feedback sessions, with 30 food policymakers and industry, public and third sector practitioners across England. The conceptual framework and outputs of the project were also reviewed by an expert from the What Works Network. The primary research findings were synthesised with the findings from the literature, to produce a set of Guiding Principles tailored to diet shift evidence. Feedback discussions with primary research participants, and other reviews, were used to test the guide. 

Further details on the project, including its conceptual framework and methods, are detailed in the Optimising Evidence Technical Report.