Metabolism is an input/output mechanism. It describe the energy turnover or input/output connected to the conversion of matter and energy, an intrinsic feature in the reproduction of any organism. Metabolism it is used also to refer to the regulatory processes that govern this complex interchange between organisms and their environment. If we admit that cities are consumption growth machines we are thrust to define them as complex systems of urban metabolism. It refers to the metabolic processes by which cities transform incoming raw materials, biomass, energy, and water into physical structures, built environment, technical devices, food, waste (Decker et al., 2000) which support a huge amount of reproductive activities performed by their inhabitants. It is also define as the total sum of the technical and socioeconomic processes that occur in cities, resulting in growth, production of energy, and elimination of waste (Kennedy 2007). Someone else might define metabolism as a set of processes taking place in the urban system involving transformation of matter and energy and the transportation of these quantities in such a way that the systems work as an organized entity.