Power and politics shape how we produce, trade and consume our food – i.e. food systems. Researchers, practitioners and policy makers recognize that power relationships at different levels influence the equity and sustainability issues in food systems. However, existing evidence has been mostly qualitative due to epistemological and methodological discrepancy. As a result, we lack understanding whether and how much power relationships lead to material consequences, and what methodologies can be employed to unpack the quantitative consequences of power. This lecture gives an overview of current food systems debate on power and politics, existing evidence that links power relationships and food system livelihoods, sustainability and equity, and emerging evidence that links power and economic and livelihood outcomes based on a case study of aquaculture sector in Vietnam. We discuss the methodology that captures certain aspects of power and politics in food systems.