In this essay, I will focus on some essential assumptions of the so-called metabolic rift theory, which sought to understand the Marxian concept of Stoffwechsel from an ecological perspective. In the first part, I will focus on the genesis of this Marxist current of ecology, dwelling in particular on the issue of Marx’s alleged productivism. Subsequently, I will shed some light on the Marxian notion of metabolism, attempting (a) to situate the concept within the nineteenth-century scientific lexicon and (b) to assess the logical and historiographical coherence of its ecologist interpretation. Ecological interpretations of social metabolism allowed for a deeper appreciation of the Marxian critical trajectory, showing its ability to grasp the structural disjuncture between social systems and the rest of nature as a necessary consequence of the capitalistic relations of production. Nevertheless, I will try to demonstrate that the concept of metabolism is not only a diagnostic and critical tool, but points to a problem that threatens virtually any post-capitalistic society.