Inspired by his religious ardor to save mankind, Graham encouraged people to take control of their health by repressing their carnal urges. These were easily stimulated by an all-American diet of flavorful, fatty, and meaty dishes. In Graham's view, the correlation between sex and health was simple: the more immoral the activity, the more bodily harm was done. And there was much immorality that needed suppressing. Graham made his name by giving popular speeches admonishing masturbation, believing it to "inflame the brain more than natural arousal," and therefore resulting in insanity. Sex more than once a month was downright pathological. "Graham was an extremist," says Dr. Ruth Clifford Engs, author of Clean Living Movements: American Cycles of Health Reform. "There were other popular health reformers at the time, but sexual urges was his particular thing."

Graham was not the first to espouse many of these ideas, but he singularly made health a moral crusade. Unsurprisingly, Graham was written off by many as a crank. But some saw him as a visionary.

Graham is considered to be one of the fathers of the early American vegetarian movement. It was Graham's particular notion that Americans could shield themselves from debilitating stimulation and find salvation through clean living and healthy food. The Graham Diet consisted of simply-prepared bland foods with lots of whole grains, mostly fruits and vegetables, and no spices, meat, alcohol or tobacco. Even pepper was banned. And whatever foods were permitted were to be eaten in small quantities at just two meals per day. Graham also advocated radical ideas about health and hygiene such as bathing regularly, taking in fresh air and sunlight, drinking clean water, wearing comfortable clothing, and exercising daily.

Graham's diet amassed thousands of devotees that came up with their own cultish name: Grahamites. They wrote to Graham testifying to his diet's life-changing effects, citing recovery from all kinds of physical and mental ailments, from nervousness and despondency to dizziness and severe headaches. As Jayme A. Sokolow notes in Eros and Modernization: Sylvester Graham, Health Reform, and the Origins of Victorian Sexuality in America: "Graham's dual obsession with food and sex was complimentary; both drives represented dangers to complete self-control and independence." Graham knew that his crusade was a difficult one, but he plodded on.

As America's first "food nut," the quality of the nation's bread became Graham's main focus in the mid-1830s. Rapid industrialization and urbanization had caused dramatic societal changes. Families were removed from the land and their food sources for the first time. Yet, Americans mostly maintained the hearty diets of their pioneer ancestors, including plenty of meat and starches, as the proliferation of factories made mass-produced bread readily available for the first time. Graham seized upon the decline of homemade bread-making with nostalgic zeal, believing in the power of the iconic nurturing, bread-baking peasant mother to unite the family.