When deciding the best method of convincing the public to adhere to U.S. Food Administration guidelines, the agency consulted modern home economists who supported a scientific approach to food. The economists advised the “wheatless” and “meatless” days, believing that “if Americans could be taught about interchangeability of proteins, fats, and carbohydrates,” they could be persuaded to adopt the concept of substitution. 9
Consequently, when USDA posters suggested consuming specific foods, they often used chart-like illustrations to suggest the rationality of the food substitution requested.
Source: Special Collections, National Agricultural Library