This paper examines the current weight-centric approach to the promotion and practice of physical activity for health. We argue that examining the assumptions and belief systems that drive physical activity promotion may provide a foundation for considering and pursuing appropriate forms of social change in the policy, prescription and practice fields. Counter perspectives and critical voices offering alternative health paradigms are systematically marginalised or silenced in this discourse. We outline the significance of a public pedagogy approach in developing alternative ways of promoting, representing and experiencing physical activity beyond weight focused perspectives. We advocate that physical activity policy makers and practitioners, including those promoting a non weight-centric approach to health need to undertake 'border crossing' and work across 'artificial' institutional barriers. The paper discusses the principles of a non-weight based, cross-disciplinary Health at Every Size (HAES) approach. It presents a critical examination of the potentials of harnessing a HAES paradigm as an alternative to a weight-loss focused physical activity intervention. At the same time, it argues that even this approach needs to better address the complexities of weight rather than search for singular, universal responses to the problems of healthism.