The city is where important exchanges of resources occur, but where what is received from the environment differs greatly from what is returned to it. Energy, water, materials and food are received, yet other waste energy, wastewater, waste materials and organic waste are returned. In nature waste equals food, where circular metabolisms enable resources to be reinvested. In cities in developing countries, not only are resources wasted, but also many people are left out of the value chain. In this paper a Social Urban Metabolism Strategy (SUMS) for Cities is proposed, where through establishing urban metabolism systems marginal communities become part of the value chain. A hypothetical case study is carried out for Quito, Ecuador. First, residential organic waste is mobilized to produce biogas for electricity generation. Second, the micro-plant is located in a community in need of economic regeneration. Third, Quito increases its own electricity generation capacity.