This paper presents a multiscale integrated analysis comparing changes in the energy metabolic pattern of China and the European Union between 2000 and 2016. The MuSIASEM method is used to explore and illustrate the entanglement over different factors, across dimensions and levels of analysis. Demographic factors observed at the level of the whole are linked to changes in the economic structure, the pattern of energy uses and the level of outsourcing (imports). When analyzing these issues for the selected case studies we found that: (i) due to their lower dependency ratio and higher workloads China presents now about 1260 h in paid work per capita, while the EU presents just 720; (ii) economic structure in China evolved rapidly moving almost 300 h per capita per year from agriculture to service, construction and industrial sectors, while it remained quite stable in the EU; (iii) the metabolic pattern of China changed dramatically by expanding its capital goods in all sectors (almost 4 times in agriculture and more than doubling in industry and services) while the EU just increased them around 10%. The quick industrialization of China (going from 20 to 60 MJ/h in paid work sector) required an extraordinary investment in the construction sector, which arrived to allocate almost 3 times more workforce and 5 times more cement per capita than the EU (already industrialized). The simultaneous reading of all these changes confirms known trends and identifies a few challenges. The apparent decoupling of economic growth from resource consumption in the EU economy is due to the outsourcing of industrial production (identified and quantified at the level of subsectors). The trajectory of economic development of China, still in the phase of industrialization, spells troubles in terms of future consumption of natural resources and pollution. The metabolic perspective used in the comparison enables to identify policy-relevant factors determining both temporary comparative advantages and dangerous locks-in. On the methodological side, the paper illustrates a few innovative features introduced in the MuSIASEM accounting framework improving the characterization of demographic and other societal aspects affecting the overall energy metabolic patterns of societies.