The Human Ecology Program at the ANU takes a systems approach to understanding sustainability issues, such as those facing modern cities and their food production systems. Focussing on food consumption as part of normal everyday behaviour is helps to get a diverse set of undergraduate students to understand the ecological consequences of their behaviour. Using metaphors mapped from the concept of ‘metabolism’ the students gain insights into how the urban form and the dominant beliefs and values of the inhabitants combine to induce major stresses on the city’s hinterlands. The metabolic imbalances of modern affluent cities appear to make them ‘obese’. Furthermore, these cities appear as ‘obesogenic’ environments (Egger and Swinburn, 1997) for a growing number of their inhabitants. Just as obesity is emerging as a primary health challenge in the Western world, so too the metabolism of cities is a primary threat to ecological health. At both the individual and urban scale these issues can be seen as ‘normal’ responses to a common systemic arrangement. Furthermore, the same kinds of intervention might lead to improvements at both scales. Once understood as problems which stem from a common core, students can see how they could take personally meaningful and achievable steps to contribute towards returning cities to equilibrium with their hinterlands. Although presented in relation to undergraduate teaching, the principles and approaches to enabling individual engagement, problem-identification, understanding and empowerment all have broader applicability.