An epidemic of metabolic disease is currently emerging in China. This review considers determinants of the metabolic syndrome in contemporary China within the context of the recent and compressed epidemiological transition. As well as considering proximal causes, such as energy imbalance resulting from increases in food availability and decreases in occupational, commuting and domestic physical activity, this review also considers life course and epigenetic influences on population health and individual risk in a transitioning population. Identifying the relative importance and mutability of epigenetic processes, influences over the life course and current environment is key to developing effective public health interventions during the current ‘demographic window’ before the costs of metabolic disease become overwhelming.