Abstract: The food/water/energy nexus is the study of the interactions and connections between these three resources, the synergies and tradeoffs that arise from the way they are managed, and the potential areas of conflict. The core of nexus thinking is that no good results can be achieved from considering these resources independently, which means that food security cannot be achieved in a context of either/both water or/and energy insecurity. All three elements have to be assured to foster sustainability, resilience, prosperity and peace. In this paper attention is focused on the challenges posed by this nexus on achieving food security, which is embodied in the first Millennium Development Goal (MDG), which seeks to halve the number of hungry people in the world between 1990 and 2015. The primary aim of the paper is to identify how the nexus mentality underlies most of the pathways that have been proposed to achieve this goal. It argues that significant shortfalls exist and need to be addressed: there is still no generally accepted definition, and identifiable metrics for assessing the extent to which a food system fosters food security are lacking. Such metrics are necessary when evaluating alternative strategies and negotiating trade-offs therein.