This section is from the book "The Hygienic System: Fasting And Sun Bathing", by Herbert M. Shelton. Also available from Amazon: The Hygienic System Vol III Fasting and Sun Bathing.
My experience agrees well with that of Carrington, who says that after a long fast the faster is ravenous and "eating must be kept under control at all costs for the few days during which it lasts." He adds that after the first few days, if controlled, "the extreme" voraciousness will disappear and "will not return." He refers to this period as the "danger period," and says that, once it has passed, there is no longer the desire "for the great bulk of food which previously existed." He points out that there is also the absence of the pre-fasting "craving" for "hot, or spicy, or stimulating viands."
This agrees well with my own experiences and observations. The period of hunger that follows a long fast lasts two weeks and more. The patient continually complains that he is not getting enough to eat. He will gain in strength and weight, he will feel good in general, but there will be that persistent demand for more food. It is not wise to try to satisfy this demand; to do so will invariably lead to overeating and often to trouble. The demand for food will be satisfied by moderate eating in two weeks or less in most cases, after which the patient will no longer be troubled by the persistent hunger. Patients who refuse to control their eating during this period, but who eat on the sly and fill up to their belly's content, commonly put on weight very rapidly, the face and other parts of the body becoming puffy, indicating a water-logged condition, and, in all cases, they undo much of the benefits they derived from the period of abstinence.
The most difficult patients to handle after the fast are those who are anxious to gain weight in a hurry. Gaining weight often becomes an obsession with these patients. They demand great quantities of food, worry because they are not gaining faster, rapidly develop into gluttons, and defeat their own ends by their over-eating, worry and tension.
The secret of the past popularity of the milk diet seems to lie here. Patients were given a fast and then put on a milk diet. They were given milk at half hour intervals all through the day and, while this over-feeding on milk destroyed much of the benefits of the fast, it satisfied the hunger of the person who had just ended a long fast. The patients put on weight in a hurry, although it was more water than flesh they accumulated, and the weight would not hold up under working conditions, the diet was a psychological success and caused the doctors who employed it less trouble then they experienced in trying to feed their patients rationally.
Professor Russel H. Chittenden confirms the view that the fast destroys the "craving" for abnormal substances and large quantities of foods. He says: "In the latter part of September, 1903, Doctor Underhill attempted to return to his original mode of living, but found difficulty in consuming the daily quantities of food he had formerly been in the habit of eating."--Physiological Economy in Nutrition, p. 78. Dr. Underhill had not been on a fast, but had been on a controlled diet for a prolonged period.
Dr. Chas. E. Page says: "Accustomed to distention from the bulky character of the old diet, if only a physiological ration of the pure and more nutritious food be swallowed, the stomach misses the stimulus of distention; time will be required (in some cases) for the stomach to remodel itself as regards size--unless a large proportion of fruit is used in conjunction with the cereals." After the preliminary period of persistent hunger has been successfully passed, the stomach seems to rest content with less food. If the patient will control himself during this period, all will be well thereafter.