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.
As knowledge of the causes of "disease" increases, it becomes increasingly evident that there are certain forms of "disease" which are in part due to food deficiencies--beri-beri, scurvy, rickets, etc. What these cases need is better nutrition, better food. Yet one can not always arbitrarily rule out the fast in "deficiency diseases." For, sometimes they are due to a lack of assimilating power on the part of the body and this is remedied by the fast. Dr. Weger, who has had much experience with fasting says: "If the body, because of its crowded nutrition, cannot assimilate vitamin-bearing food, it can be brought into the condition to do this by a purifying fast."
The value of the fast in rickets and certain "diseases" of childhood is well established. Its value in anemia has been discussed elsewhere. There is no reason why fasting cannot be employed in dietary deficiencies with great benefit. Indeed the loss of appetite seen in men and animals fed on greatly deficient diets indicates strongly that a fast is called for.
The experienced practitioner need not hesitate to place his patients upon a fast although some of them will require careful watching. If he lacks experience, some of his patients may be handled without the fast.