Although strategies to tackle obesity have led to renewed debate about the relationship between the body and urban form the (im)mobilities of fat through bodies, cities, and infrastructure reveal a complex web of urban metabolisms. We argue that, to understand the mobilities of fat in a city context, metaphors of urban metabolism become important. The relationships between different flows are contingent and the mobilities of fat in bodies (as individuals), cities (as a collective site of action), and sewers (as infrastructure), we argue, highlight a multiplicity of urban metabolisms, each with different interconnectivities and forms of instability. In the paper we show how, in North America, in response to the rising numbers of â��obese bodiesâ�� there has been the mobilisation of the concept of â��fat citiesâ��, involving renewed debate about the relationship between bodies and the city, provoked largely by the innovative representations of Menâ��s Fitness magazine. However, we shift focus to highlight the problems of fat in infrastructure, focusing specifically on the experience in US cities of sewer blockages that reveal quite different sets of processes within which fat is embedded. Strategies of intervention at the level of the body, the city collective, and the sewer involve prevention, removal, and acceptance, each revealing a multiplicity of metabolisms as well as the partial interconnections between them.