Rapid and unplanned urbanization and lack of quality food are interrelated problems caused mainly by population growth. In developing countries, the cumulative effects of these problems have led to increased food dependency of the informal city on the formal city. Informal settlements in South America have limited resources, and their agro-food systems predominantly function linearly, while resource stocks and flows are not always optimally managed and exploited. However, they remain on rich urban dynamics and well-established community networks that should be exploited to generate agro-food resources based on deeper knowledge of existing flows. Urban agriculture should be promoted using a territorial and ecosystemic approach through urban metabolism and circular economy strategies to optimize the agro-food system's flows and stocks. In light of this consideration, the research will produce a theoretical model of metabolic assessment to improve food security at the neighborhood level in informal settlements in South America. The model will be applied to the city of Lima, Peru. Then, a pilot study will be conducted in Lima's informal settlements to validate the theoretical model and provide local stakeholders with tools to perform spatial re-qualifications of "spaces of opportunities" in informal settlements using geo-referenced information systems. Finally, circular economy scenarios will be projected based on the method "Sustainability assessment framework for scenarios" (SAFS) to improve food security.