Childhood obesity is increasing worldwide, raising alarm about future trends of cardiovascular disease, diabetes and cancer. This article discusses what may underlie our failure to respond effectively to the obesity epidemic, and presents a wider perspective for future research and public health agendas. So far targeting individual-level determinants and clinical aspects of childhood obesity has produced limited success. There is growing interest in understanding the wider determinants of obesity such as the built environment (e.g. walkability), social interactions, food marketing and prices, but much needs to be learned. Particularly, we need to identify distal modifiable factors with multiple potential that would make them attractive for people and policymakers alike. For example, walking-biking-friendly cities can reduce obesity as well as energy cosumption, air pollution and traffic delays. Such agenda needs to be driven by strong evidence from research involving multi-level influences on behaviour, as well as the study of wider politico-economic trends affecting people’s choices. This article highlights available evidence and arguments for research and policy needed to curb the obesity epidemic. The upstream approach underlying these arguments aims to make healthy choices not only the most rational, but also the most feasible and affordable.