This dissertation traces the history of a dietary reform movement, which sought “right eating” in early twentieth-century Japan. The movement revolved around the concept of shokuyō, which broadly referred to the art of nourishing life and vitality—yōjō—through proper eating. Its central proposition was a call for the return to “natural and traditional” foodways with a particular emphasis on the consumption of unpolished rice and largely plant-based foods. Chapter One explores how the movement and discourse of shokuyō came into being and developed as a reaction against modern transformations of Japanese society since the Meiji Restoration. It situates the shokuyō movement within the context of discourses on hygiene, health, and the overarching project of civilization and enlightenment. Although the late Meiji shokuyō advocates sought to associate its ideal diet within the boundaries of orderliness of nature and civil morality, the way to understand the relationship between food and health became increasingly overshadowed by the ascendance of institutionalized nutrition science in the 1920s. Chapter Two looks at how “efficiency” and “rationalization” became catchwords in food-related public campaigns and medical discourse in which the concept of shokuyō was superseded by that of eiyō (nutrition). In spite of this, the shokuyō movement, evolved toward another direction with a new critique of modern medicine. Chapter Three concerns this transformation by analyzing how Sakurazawa Yukikazu reconceptualized shokuyō theories as “Natural Medicine” by drawing on contemporary French critiques of biomedicine and Shinto ideology. The following two chapters trace the movement’s transformation in the 1930s from an esoteric and upper-class-centered one into a large-scale movement targeting wider sectors of society. Chapter Four looks at how the campaigners actively intervened in the wartime standardization of brown rice as the national staple in face of total war. Chapter Five on the other hand analyzes the shokuyō movement’s crusade against sugar consumption in Japanese migrants’ diets in Manchuria, showing how they attempted to bring together tenets of “eating right” and the project of Empire. This dissertation ultimately argues that shokuyō’s “traditionalist” and “natural” dietary persuasion fed into a cultural nationalist and imperialist political imagination grounded in a holistic understanding of the body, health, and environment.