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