The view that a healthy diet was low in fats and high in carbohydrates became mainstream and widely accepted during the second half of the 20th century. But discussions about diet, disease, and health take place in a highly politicized arena, and this diet was the subject of considerable controversy. This chapter examines the period from the 1940s, when awareness of the increasing incidence of CHD began to grow, to 1985, the year the National Cholesterol Education Program (NCEP) began its effort to sell the anti-fat, anti-cholesterol message to the nation. This campaign marked a victory for advocates of fat reduction over skeptics who continued to question the efficacy of low fat diets as a means of preventing disease.