The planning profession has been advocated as an untapped resource for obesity prevention, but little is known about how planners view their roles and responsibilities in this area. This paper investigates the role of planners in the Healthy Towns programme in England, and explores the limits and potential for obesity prevention within planning policy and practice. Using a qualitative approach, 23 planning stakeholders were interviewed, identifying the potential for planning in public health, particularly the 'health proofing' of local planning policy. National and local governments should better align planning and health policies to support collaboration between planners and public health practitioners.