Hi Jean-Louis!!
  Thanks for your great letter!  I have some thoughts.

You write:
> <<  --Myth 1: when you fast, after a few days, you have more energy.
> You can walk 20 miles/day, run longer, etc. >>

Ten years ago I knew nothing about fasting at all, except I had (tried) to
read "The Science and Fine Art of Fasting" by Shelton (thumbed through and
read spots), "Rational Fasting" by Arnold Ehret and "The Miracle of Fasting"
by Paul Bragg (both of which I read in entirety). Those were the only books I
had ever come across anywhere that dealt with the subject.  It must have
been in one of those that I read stories about men accomplishing incredible
physical feats during extremely long fasts, out-running younger, fit,
"eating" men, etc.  So I never understood the concept of fasting being a
period of rest, and I figured I would have tons of energy. And - amazing and
puzzling to me now - I did!!  I remember doing one 15-day fast while running
my usual 6 miles per day, and organizing and  leading a huge three-day
workshop that involved finding people places to sleep all over town,
organizing huge meals, preparing and leading group lectures and workshops,
 etc. - the kind of thing that is usually extremely exhausting to anyone.
 Other than losing my voice a little from talking so much, I felt great and
energetic through it all. And no one ever knew I was fasting.

Today, the 7th day of my current fast, I have all I can do to go up a flight
of steps without stopping to pant in the middle, and other than trips into my
office to read email, I am spending all day everyday in bed, feeling very,
very, very weak and physically tired.

Is this because I now understand that I should be resting for maximum
benefit, so I'm paying attention to my body instead of overriding its needs
with my mind? Who knows!!

You write:
> <<  Dark urine may result from autolysis (I'm not sure): your body
> uses its muscle protein to fulfill its daily requirements in protein
> and glucose. But after a few days, as the metabolism slows down and
> the nervous system utilizes more fat instead of glucose, the rate of
> muscle loss is lower. >>

My understanding is that the body uses glucose available in the blood during
the first day, until it is depleted (very quickly). Then it goes to glycogen
stores to extract glucose there (stored in muscle tissue - thus resulting in
loss of protein and muscle mass). The body does not "want" to waste muscle
tissue this way, so when still no glucose is coming in from food, it then
resorts to another mechanism (gluconeogenisis) where it "cumbersomely"
synthesizes glucose from compounds in the liver. But by the 3rd-5th day the
body has converted to another ATP production system, ketosis, where it is
able to synthesize and use ketones from the fat stores, instead of using
glucose.  And in addition it extracts and uses whatever is usable from
autolysis of (HOPEFULLY HOPEFULLY HOPEFULLY IN MY CASE!!!!) fibroids (I have
some uterine fibroids), tumours, mineral deposits in joints, etc. etc. This
is also called "protein sparing" because that's what it is -sparing lean body
tissue and using instead adipose tissue. And I have understood that this
process of ketosis is extremely inefficient for producing adequate amounts of
ATP, therefore we don't have as much energy; and that if one taxes the body
with physical (or mental) activity (or "stresses") the body is forced to
resort to glycolysis again (extraction of glucose from muscle tissue)  to
provide the necessary energy requirements, thus wasting muscle mass (no
longer "protein-sparing"). Is this basically the understanding that you have?
Or a little different?

Thanks again for your letter. Its really a great feeling to be able to talk
about fasting with other people who have done it or thought about it  - WHILE
fasting!  Its a first for me!

Lots of Love,  Liza