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.
I take the position that the time to fast is when it is needed. I am of the decided opinion that delay pays no dividends; that, due to the fact that the progressive development of pathological changes in the structures of the body with the consequent impairment of its functions does not cease until its cause has been completely and thoroughly removed, putting off the time for a fast only invites added troubles and makes a longer fast necessary, if indeed, it does not make the fast futile. I do not believe that any condition of impaired health should be tolerated and permitted to become greater. Now is the time to begin the work of restoring good health; not next week, next summer, or next year.
There has been much discussion of what time of year is best in which to fast. Mr. Purinton advises all prospective fasters to "choose summer or spring for the conquest fast," but, while I agree with him that warm weather is, on the whole, the best time for a fast, I advise that no sufferer delay a needed fast until spring or summer, but to take it when needed. As Oswald says: "Winter is not the worst time for a fast, it may even be the best, to judge from the phenomena of hibernation."--Fasting, Hydrotherapy and Exercise, p. 65. Louis Kuhne called attention to the fact that many animals eat far less in winter than in summer. Theoretically, at least, less food is required to maintain body heat in summer than in winter; but the winter faster who is kept warm may fast with the greatest of ease.
I agree, however, with Carrington that it is easier to fast in summer than in winter. The sense of chilliness that the faster experiences is greater in winter than it is in the warm months. Although this sense of chilliness does not correspond with the real cold of the outside or room temperature and, curiously enough, a thermometer will often show that the temperature of the faster is one or more degrees higher than before he undertook the fast, in spite of the fact that he has the feeling of being cold. He should be kept warm.
This, in my opinion, should not deter the man or woman who needs a fast from taking one at any season of the year. A fast should not be delayed because of some slight discomfort. If the faster is kept in bed, as he should be, with a hot jug to his feet, the feeling of coldness is easily controlled.