What is the Phase 1 Diet? The Phase 1 is a diet designed to starve an organism – fungus. Parasitic yeasts and fungi can infect human tissue, causing miserable symptoms. Once on board, these organisms must have their favorite food source, sugar, to survive. The Phase 1 Diet seeks to starve and rid the body of those parasitic organisms, while eliminating foods that are commonly contaminated with fungal poisons known as mycotoxins.