The application of the biological concept of metabolism (‘Stoffwechsel’) to social systems can be traced back to Marx who, influenced by Liebig and Moleschott, talked about the ‘metabolism between man and nature as mediated by the labour process’. Such a biophysical approach to the economy was not unusual at the turn of the nineteenth century but arguably did not form an integrated school of thought until recently (Martinez Alier and Schlupmann, 1987). This biological analogy grew from the observation that biological systems (organisms, but also higher-level systems such as ecosystems) and socio-economic systems (human societies, economies, companies, households, etc.) decisively depend on a continuous throughput of energy and materials in order to maintain their internal structure (Fischer-Kowalski and Haberl, 1993).
Today, a number of standardised methods exist for accounting for energy flow, material flow and land use aspects, provides the basis for empirical analyses of the biophysical structure of economies and for developing strategies towards more sustainable production and consumption patterns. These methods include material and energy flow analysis (MEFA), life cycle analysis (LCA), life cycle inventory (LCI) and life cycle impact assessment (LCIA), and also input-output analysis (IOA) (Weisz, 2006). Other instruments in the social metabolic toolkit include HANPP, EROI and Virtual Water, as well as related concepts such as ecological footprinting, and ecological rucksacks.