The energy efficiency and consumption of mobile networks have received increasing attention from academics and industry in recent years. This has been provoked by rapid increases in mobile data traffic and projected further rapid increases over the next decade. As a result, dramatic improvements in the energy efficiency of mobile networks are required to ensure that future traffic levels are both environmentally and economically sustainable. In this context, a good deal of research has focused on technologies and strategies that can improve the energy efficiency of 5G and future mobile networks more broadly. However, existing reviews in the field of green or sustainable mobile communications on the topic of the energy use implications of 5G overlook a number of issues that broader literatures on the energy use impacts of ICTs suggest could be significant. Addressing this gap, we conduct a literature review to examine whole network level assessments of the operational energy use implications of 5G, the embodied energy use associated with 5G, and indirect effects associated with 5G-driven changes in user behaviour and patterns of consumption and production in other sectors of the economy. In general, we find that these issues and their energy use implications have received insufficient attention in publicly available studies on the energy use impacts of 5G.