This chapter focuses on food systems using an innovative dual approach. First of all, by considering them in interaction with energy and chemical systems within ecosystems, it poses the question of resource allocation (land and biomass). Second, a socioeconomic approach then highlights the diversity of these food systems. Different types of systems co-exist and reflect different ways of producing, processing, distributing and consuming food products. The 'global' food system is a constantly changing combination of these different types of systems, ail of which influence each other. Thanks to this dual approach to food systems, new research questions have emerged. New analytical frameworks would enable a clearer understanding of the interconnections between food systems within ecosystems, on the one hand, and their diversity and constant recombination on the other.