A Conceptual Model for Understanding the Sustainability of Food Consumption Based on the Nova Food Classification

Contemporary food systems face growing challenges in simultaneously promoting human health, environmental sustainability, social equity, and cultural adequacy. Although sustainable diets have gained prominence in research and policy, current assessment frameworks remain fragmented and rarely integrate food processing as a structural dimension shaping food system organisation and sustainability outcomes. Nevertheless, growing evidence indicates that ultra-processed foods represent not only negative health outcomes but also a structural expression of modern food systems, with environmental, economic, and sociocultural implications. In this context, this study proposes a theoretical conceptual model, integrating the degree of food processing, based on the Nova food classification, into the dimensions of sustainable diets, structuring evidence on how food processing operates across food system stages and shapes sustainability outcomes. The model was developed through a systematic model-building process, including expert validation using the Delphi technique. The proposed framework illustrates how diets based on unprocessed and minimally processed foods, compared with ultra-processed foods, are associated with distinct sustainability trajectories, including greater support for biodiversity conservation, local food systems, cultural and culinary practices, and higher nutritional quality, while highlighting interactions across food system components. Rather than establishing causal relationships, the model organises existing evidence, identifies key knowledge gaps, and provides an integrative framework to support future empirical research and policy-oriented analyses. By incorporating food processing as a structural characteristic of food systems into the analysis of diet sustainability, the model broadens understanding of contemporary food system challenges and highlights the structural role of ultra-processing in shaping sustainability outcomes, supporting more systematic assessments and informing policies toward more sustainable food systems.