From: bradbury@sftwks.UUCP (Robert Bradbury)
Newsgroups: rec.food.veg,misc.health.alternative,sci.med.nutrition
Subject: Re: "The miracle of fasting" by Paul C. Bragg
Summary: Energy generation during fasting/calorie restriction
Date: 17 Jan 93 01:40:10 GMT
Followup-To: rec.food.veg
Organization: Softworks Ltd, Seattle, WA

In article <1993Jan15.165018.15492@walter.bellcore.com>
  kenl@origami.cc.bellcore.com (Ken Lehner) writes:
>In article <1993Jan14.235554.15921@imagen.com>, avi@eagle.imagen.com writes:
>
>|> For example, he walked 30 miles non-stop in Death Valley, CA in August
>|> (one of the Hottest places in the world) WHILE fasting and he was in
>|> his 50's and the 10 young College Athlethes who were NOT fasting who
>|> joined him, all collapsed before him and none of them finished the 30 mile
>|> track, but him. If I remember correctly, (and I could be wrong on this
>|> detail) he was on his 7th day of a 10-day fast ! 
>
>I'm most skeptical about this anecdote.  Living for 7 days requires
>energy:  where does he get it from?  Glycogen in the muscles must be
>replenished.  He either eats or he consumes body fat (and/or muscle). If
>he has such a healthy diet, he can't have very much body fat to spare
>(like 4 pounds in a 7 day fast).

The energy comes from the proteins in the body.  After all glucose,
glycogen and fat are exhausted the body relies on gluconeogenesis
(generation of glucose from amino acids) for energy.  Now, if this
were to continue for an extended period of time the person would
waste away (as is seen during starvation) but for the short periods
associated with fasts our bodies can handle it.  Do you really think
the primitive man would go through life getting 3 square meals a day,
every day?  All animal species will encounter periods when there are
food shortages and must have adaptive mechanisms to handle it.
Now, the interesting question is "why" do fasting or calorie
restriction reduce the aging rate?  Since you body needs amino
acids for gluconeogenesis it directs cells to break down proteins
and release amino acids.  Cells have natural pathways which break
down old/damaged proteins which seem to be accelerated under conditions
of calorie restriction.  Proteins have an "average" half-life of 24 hours,
some last only minutes, others several days.  In the calorie restricted
state the half-life is probably shifted so proteins are degraded before
they have sustained as much damage as in a "well-fed" individual.
Less damaged proteins allows your body to function more efficiently.
So, I'm not suprised that a fasting individual could outperform a
well-fed individual.
>
>In the world of triathlons, there is a condition known as "bonking".  It
>is a state of light-headedness, inability to exert much force, and a
>serious desire to eat.  It occurs after the body has depleted it's
>available energy resources, and can result after an hour or two of aerobic
>exercise.  I wasn't aware of anything that could prevent this except for
>correct fueling before and during the activity.
>
The "bonking" results because the body has run out of available fuel.
It takes at least several hours to turn on the genes involved in
protein breakdown and gluconeogenesis and get them functioning at
a level which can support physical activity.  They also probably
were not designed to support the activity required in marathon
running (note the fasting individual was *walking*).  Our bodies
aren't designed for long term aerobic activity, there are obviously
other animals (e.g. migratory birds) who can expend a great deal
of energy over a long time and have no problems with it.

>Walking 30 miles in an extremely hot, arid environment has little to do
>with fasting, and everything to do with correct hydration and one's ability
>to maintain body temperature.  Just why did these College Athletes (and
>why the caps?) collapse?  To what aspect of fasting does he attribute this
>"ability", and just what is it that happens to his physiology?  Name some
>"incredible athletic feats" of his (walking 30 miles isn't one of them, at
>least to me).  Incredible is biking across the US in under 10 days;
>incredible (and not really bright :^) is scaling Everest without
>carrying oxygen; incredible is the 65 year old woman who ran something
>like 390 miles in 6 days (and you BET she was eating).

The body responds to conditions of "heat" or "stress" by manufacturing
"heat-shock" proteins.  These are proteins found in all animals and
play a key role in maintaining proteins in their proper folded form
(heat tends to cause proteins to unfold and function improperly).
I would suspect that a fasting individual probably has higher levels
of heat shock proteins (low food intake is considered "stress") than
well-fed individuals and that would easily explain his better ability
to tolerate the heat.

"Incredible" is something which depends on your perspective.
I seem to remember a fairy-tale about a hare and a tortise....
While individuals who fast periodically may not be able to run
marathons he just might outlive those people who choose to do that.
-- 
Robert Bradbury			uunet!sftwks!bradbury

Death is an imposition on the human race, and no longer acceptable
				Alan Harrington, The Immortalist (1969)
Newsgroups: rec.food.veg