This chapter explains how theories of gelatin and osmazome were eventually replaced by a more modern approach to the diet. It illustrates this change by comparing two very similar products that emerged over the space of just a decade: a substance called Osmazome Food, which was promoted by Alexis Soyer, and one known as Extractum Carnis, or “extract of meat,” which was promoted by the founder of modern biochemistry, Justus Liebig. These two products were essentially the same, but were marketed in radically different ways: the former framed by classical dietetics; the latter by modern nutritional science. The chapter shows how classical dietetic tradition, which had spread throughout Europe in the Renaissance, died away with modern biochemistry, and Liebig's science shifted attention inside the body. This had four main implications which profoundly changed how food was judged, how nutritional authority was conducted, how food was removed from its social context, and how food became a tool of progress.