The health of children in affluent economies has become closely tied to the ideal of a normative body weight achieved by monitoring and balancing diet and physical activity. As a result, the education of young people on how to avoid becoming fat begins at an early age through the language and practices of families, the messages embedded in children's media, and through formal schooling. In this paper we use the concept of biopedagogies to investigate how discourses that connect food, the body and health come together on Internet websites to instruct children on how they should come to know and act on themselves in order to be(come) healthy bio-citizens.