The paper argues that the problem of obesity can usefully be seen as illustrating a new kind of market failure. At the heart of such failures is the emergence of a sub-optimal choice environment which, though derived from a large number of small individual optimising decisions, is not the choice environment that people would choose if they were able to choose the environment itself. This idea is claimed to be consistent with modern economic theories of freedom of choice and applicable particularly to choice environments that emerge in highly competitive market situations. The retail supply of food and consumer credit is discussed by way of example. Concluding, the paper develops the concept of a ‘deliberative economy’ as an alternative to liberal paternalism and explores conditions under which such an approach to social choice might deliver desirable outcomes.