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.
There have been men who approved of fasting in acute disease, but not in chronic disease, on the ground that so long as nature demands food, food should be taken. They have insisted upon being guided by instinct in this matter of eating or fasting. The demand for instinctive eating, instinctive fasting and instinctive living is quite fundamentally sound, but we must learn to discriminate between instinctive demands and morbid cravings. Morbid cravings are strengthened, not overcome, by appeasing them. Take the case of the patient, previously mentioned, who was ravenous, ate a meal and shortly thereafter, vomited this along with food that had been consumed at noon the day before; how can we think of his supposed desire for food as an instinctive demand? It seems the height of absurdity to contend that appetite, such as he had before he ate supper that evening, should be satisfied. To me such contentions are on a par with the claim that the craving for opium, alcohol, tobacco, arsenic, etc., should be satisfied.