With the recent discussion on the list in regard to the thrifty genotype
hypothesis and periods of starvation, can anyone offer an evolutionary
rationale for why the practice of fasting (intentional, controlled,
monitored "starvation" within safe limits, if you will) should be not
merely adaptive in an undependable environment, but actually beneficial to
health? That is what is claimed, at any rate, by numerous alternative
health advocates who claim great things for it and that it "renews" the
body. (Analogies are sometimes made with animals that seasonally fast like
hibernating bears, and who (supposedly) live longer than non-hibernating
animals of the same size; caterpillars turning into butterflies while
ingesting no food and existing on stored nutritional reserves; fur bull
seals expending enormous amounts of energy at the height of the mating
season while fasting during a time their fertility must be at a high, etc.)

There has been some work by a Scandinavian research group with fasting and
arthritis that someone here on the list provided me a reference about some
time back, but I have not gotten around to checking it out. [Kjeldsen-Kragh
et al. "Antibodies against dietary antigens in rheumatoid arthritis
patients treated with fasting and a one year vegetarian diet." Clin Exp
Rhematol 1995;13:167-72.]

One hypothesis I have heard suggested is that in itself fasting may be of
note not so much for anything it does on its own, but rather that it simply
temporarily eliminates potentially offending foods in the diet that may be
adversely impacting one's metabolism. Thus if one were to subsist on a diet
not containing any such potentially offending foods, the thinking goes that
one would see no material difference between the positive benefits of that
vis-a-vis fasting. The standard theory among alternative health advocates,
however, is that fasting has unique things to offer because it "detoxifies"
the body. But on the other hand, I have heard it asserted (unfortunately no
one has been able to produce references for this point) that there are
clinical studies showing that the production of certain enyzmes specific to
certain detoxification pathways in the body is negatively impacted by
fasting.

Several years ago I did some personal experimentation with lengthy fasting,
and seemed to get relief from symptoms I had been experiencing as well as
improvement in sensitive blood sugar. However, I also experienced fasting
to be one of the most extreme physical stresses I have ever experienced.
(Some individuals apparently find it fairly easy, however.) Because of
this, I have in retrospect become much more skeptical and wondered if it is
really such a positive thing, and find it difficult to conceive how there
could be any evolutionary justification for it other than as a survival
mechanism.

I find this a confusing area and wondered if anyone here has insights to
offer regarding evolutionary adaptation and starvation/fasting that may
illuminate the issue. Thanks.

--Ward Nicholson <[log in to unmask]>