My purpose in this paper is to consider the relationship between, on the one hand, critical social science and, on the other hand, existing and emerging sciences of the body. Taking my lead from the sociologist, Steve Fuller, I discuss the ways in which some social scientists, both within and outside physical education and sport, have engaged with the idea of an "obesity epidemic", generally falling between the distant poles of naive acceptance and ideological rejection. Using new and emerging forms of biological determinism as a second example, I describe the colonising tendencies of particular medical and biological sciences, such that robustly social understandings of the body and less instrumental approaches to physical education are, in some senses, at risk. A future social science of the body needs to be more scientifically literate in order for the excesses of science to be managed or tamed. In other words, the job of the social scientist is to be able to speak more than one language.