Global food systems continue to negatively affect a number of human and ecological systems. These impacts are driven by the powerful discourses and institutions that influence everyday policies and behaviours. These competing discourses create a challenge context for food systems solutions, with high stakes in decision making, knowledge uncertainty, significant ethical issues, and political power imbalances. This makes food systems an important case to pursue post-normal interdisciplinary science that focuses on human and ecological interactions. To study these interactions, we employ a dynamic systems framework drawn from human ecology to show the links between competing food discourses and the influence they have on different institutional, human wellbeing, and ecological outcomes. Our systems-based framework draws specific attention to the influence of the dominant discourses governing change in food systems and guides reflection on the dimensions of justice and sustainability promoted by those discourses. We focus on food security and food sovereignty as two major food discourses that influence the food systems’ behaviour. We note that, conventionally understood, the food security discourse fails to adequately address the broader social, justice, and environmental aspects of food systems. These aspects are the central concern of food sovereignty and at a scale where democratic governance of food systems with greater concern for social and ecological wellbeing is proposed. Using the literature within our framework, we discuss the extent to which the discourses promote solutions in the form of more equitable food systems, sustainable intensification, agroecology, and diversified diets. Our systems analysis allows us to hypothesise how the different discourses influence food systems behaviour and leads us to identify the fundamental importance of social relations in a food system, which go far beyond understanding food security merely as the adequate provision of a food commodity. We conclude by suggested greater attention in research into the complex nature of food governance and the political dimensions of stakeholder participation in food systems.