This is part of a series of lectures on Qin Bowei's 56 methods. It focuses on food-related illness. This lecture covers the source, causes, mechanism, locations, disease manifestations, and presenting symptoms, presenting the broad picture of Food. The lecture also discusses the associated treatment principles of Food. Key diagnostic criteria for each principle, the associated flagship formula for each, how to modify it, how it relates to classical Chinese medicine will also be discussed. Numerous case studies will be used in this lecture to demonstrate how the system can be used clinically.