Here is an excerpt from the chapter: "The length of the fast"
A 'finish fast' does not always mean a long fast. It does not mean a fast until all of the body's food reserves are exhausted. It is a curious fact that hunger will return in three days, even where there are abundant reserves on hand, if three days are all that are required for the patient to get well; whereas, it will not return for five weeks or longer, even where there are fewer reserves on hand, providing this time is required for the body to eliminate its accumulated toxins. Fortunately, in most cases it will be perfectly safe for the patient to fast until hunger returns.