In Colombia early in the twentieth century, a field of research began to take shape that looked at work and the physiology of diet, centered on the analogy of the human body as a heat engine that transforms energy. Starting with the energy unit of calories, foods were translated into the amount of fuel the body-machine needed for optimal performance depending on the work performed and environmental conditions. The main objective of this article is to highlight the role that this energy-centric conception of the body played in configuring a series of educational and public hygiene campaigns carried out in Colombia between 1890 and 1940. I argue that these social engineering actions, aimed at achieving the physiological regeneration of the population, formed part of the local eugenics movement, since the ideal of producing efficient working bodies was conceived of as a heritable characteristic that could improve future generations of workers. With this I highlight an unexplored aspect in the historical and local significance of the biological and its relationship to the way social problems of that time were understood. By historicizing both the social and the biological, I propose a research approach that contrasts with the usual distinction between the natural and the cultural present in some of the historiography on eugenics and race.