In this presentation we will introduce several aspects and levels of insight into the application of systems thinking for the prevention of childhood obesity. Examples will be drawn from existing and previously completed community-based trials of whole of community efforts to prevent childhood obesity. Examples will be given of different levels of systems insight from awareness of interrelations and complexity through to formal mathematical expression of system behaviours. Specific system analysis techniques including system dynamics, social network analysis and agent-based models will be introduced and discussed. Preliminary results of a five-year trial will be presented with an emphasis on food and nutrition.