The devastating economic and social impact of COVID-19 and the war in Ukraine has exacerbated poverty and food insecurity, making it harder for people to access food. Based on a multidimensional understanding of food insecurity, this study focuses on one of the most challenging dimensions for affluent societies, namely, the economic access to food. Therefore, the research aims to develop an innovative Food Affordability Index (FIA) that captures the inter-territorial inequalities and critical problems created by the economic disruptions in the local food system that prevent people from eating healthy. The index is based on a survey of the prices of products suitable for healthy eating in thirty shops in Rome, Italy. A distinction was made both by the type of distribution channel (e.g. discount and supermarket) and by the area in which the survey was conducted, i.e., the 15 municipalities of Rome. This study sheds light on the problem of food insecurity and highlights areas where households are far from an ideal healthy diet. Understanding the spatial distribution of economic inequalities in access to healthy food seems crucial for the implementation of targeted policies and programmes to address this problem, which is increasingly structural in affluent societies.