This paper examines the literature of Upton Sinclair, famed American author of The Jungle, and how this 1906 novel led to the formation of Theodore Roosevelt’s Food and Drug Administration. I am particularly interested in Sinclair’s fascination with fasting fads, which reflect a larger Progressive-era preoccupation with physical fitness and the white male body. American literary naturalism, the late nineteenth and early twentieth-century movement to which Sinclair contributes, is a literature of and about human hunger. Many scholars have focused on The Jungle, a seminal book that revolutionized the food industry; however, little work has been done on the narratives about fasting and fitness that followed. My work therefore draws attention to a dietary discourse that reveals a great deal about early twentieth-century conceptions of masculinity, health, and the body. This paper is part of a larger effort to reconcile a counter-narrative of culturally disordered eating and self-restraint on the one hand with the ecological ethics so central to naturalism’s politically radical sentiments on the other.