The global food system is responsible for ~26% of greenhouse gas emissions, 70% of freshwater use, and occupies nearly 50% of habitable land (1) . This makes food production a significant driver of environmental degradation. Consequently, the concept of sustainable diets has gained significant attention in recent years as policymakers and researchers seek to mitigate these impacts. Systems approaches provide a promising framework for addressing the complex, interconnected factors influencing diet sustainability (2) . However, studying sustainable diets as part of a complex system presents significant challenges, as it requires capturing dynamic interactions between environmental, economic, and social factors (3) . A variety of systems approaches have been used to model these interactions, but there has been no review evaluating their application in this field. This study presents a scoping review (4) to answer the following research question: What methods have been employed in systems approaches to examine the factors influencing sustainable diets in sustainable dietary research? A comprehensive search was conducted across MEDLINE, SCOPUS, Web of Science, and Swansea University library database, identifying eligible peer-reviewed studies, that applied systems methods to sustainable diets/food systems. 43 papers were included. In this review, the results for systems methodologies were separated into formal methods and framing approaches as these two broad types of approaches emerged after analysing the results. For formal methods, the predominant methodology applied to sustainable diet was agent-based modelling (n = 15), followed by systems mapping (n = 6), simulation modelling (n = 6), systems dynamic (n = 4). The least common methodological categories were network analysis (n = 3), multi-criteria decision making (n = 1) and optimisation modelling (n = 1). For framing approaches, systems thinking and systems framing had four eligible studies each. Out of the 43 studies that met the criteria, 18 used participatory methods. Further findings indicated that while systems approaches offer valuable insights into the complexity of adherence to a sustainable diet, their application is often misaligned, particularly in accounting for diverse regions and socio-economic contexts. However, the application of systems approaches in the field of sustainable diets remains in its infancy, with research largely focused on descriptive analyses rather than more advanced methodologies. To progress there is a need to further refine systems methodologies, enhance their applicability across different contexts, and set a systematic research agenda that encompasses the design, implementation, and evaluation of systems-level interventions to drive meaningful change.
McIntosh et al. (Fri,) studied this question.