Metabolism is a hot topic in science, from the epidemic of “metabolic diseases” such as obesity and diabetes to the rediscovery of altered “cancer metabolism” as a defining characteristic of malignant cells. As is often the case, once a topic has become in vogue, its name ceases to have meaning as researchers try to identify their work as relevant to the latest fashion. Thus, it is opportune to reconsider not only the meaning of “metabolism” but also whether the rebirth of metabolic research is incorporating many of the lessons learned through years of study in the last century.