Hello Mighty.Sun.Tzu,
In answer to.........

"Just wondering, is the body "smart enough" at this stage and throughout the fast to take the worst tissue first (dead or diseased, or the very weakest)... or does it take some good and some bad at random"?

A.
The process of Autolysis..........................
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch5.htm

is very selective and discerning in the very early stages of the fast and where after the conversion from glucose to ketones as a fuel source, this process takes immediate effect in the burning of effluent matter, toxins, morbid matter and so on as a first choice. This is why the worst symptoms of detox occur within the first 5 days.

Shelton.......
"It will be observed that during the fast the tissues do not all waste at an equal rate; those that are not essential are utilized most rapidly, those least essential less rapidly and those most essential not at all at first and only slowly at the last. Nature always favors the most vital organs. The fat disappears first, and then the other tissues in the inverse order of their usefulness. The essential tissues obtain their nourishment from the less essential, by enzymic action, a process which has been termed autolysis.
Only in a very special sense does the body "start eating itself" when one begins to fast. It never consumes its tissues indiscriminately, but, true to its rule of always favoring its most vital organs, it uses up the least useful tissues first. Selective action is exercised from the beginning and the most rigid economy is exercised in appropriating its food reserves in sustaining the heart, lungs, brain, nerves and other vital organs. Even the respiratory muscles are more carefully guarded than the other muscles of the skeleton"........................
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch7.htm


Shelton...........
"When food is withdrawn from man or animal, the demand for substance with which to maintain the structures and functions of the vital tissues is thrown upon the reserves of the fasting organism..................

The fasting organism makes the most of the material at hand----it spins out the inevitable loss as far as possible; indeed, those substances which are absolutely essential for the preservation of the vital spark, or for the continuance of the motion of such necessary organs as the heart and central nervous system, are only used up when the supply from other organs has almost entirely failed. Fats and any store of glycogen are first used up, along with part of the proteins, until, when from a quarter to a half of the total body weight has been lost, the machine stops for want of motive power.
If the fasting continues, readjustments are made to secure minimum demands upon the nutritive stores; as the fast progresses, the body tends to conserve its supplies by lessening activity both physical and physiological, so that the rate of loss gradually diminishes"..............
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch4.htm



And.......
"The way this is worded it sounds like day 11 and beyond, there is a decline in fat burning compared to day 10. If this is what you mean, do the protein grams burned in day 11 and beyond remain the same as in day ten, but fat burning is slightly diminished because the body is needing a bit less fuel"?.

A.
Indeed yes. There is a decline in fat-burning as the fast progresses. I have lost count as to how many posts we have had on the forum from fasters whose weightloss has "stagnated", and are able to go for days at a time without any apparent weightloss: even when taking into account that they are not drinking water to excess.
All of the vital nutrient reserves are used both efficiently and economically by the innate wisdom of the body.



And......
"As part of protein conservation, the body also begins seeking out all non-body-protein sources of fuel: nonessential cellular masses such as fibroid tumors and degenerative tissues, bacteria, viruses, or any other compounds in the body that can be used for fuel."

"This is an extension of my first question, but does this happen right away (in the first couple of days) too, or does it only "begin" to happen at some point later? And as this is happening, is there zero healthy muscle tissue being burned as long as there is something unhealthy for the body to take instead"?

A.
Immediately, but there will always be some muscle loss in the need for glycogen by breaking down the amino acids in muscle tissue and using them in the liver for gluconeogenesis, or the making of glucose. There will always be a small demand for glucose by some parts of the body during even the most extended fast on a daily basis, but these amounts are minimal...........1-2 pounds of muscle mass on a 30 day water fast; an insignificant amount which is easily replaced post-fast.


Regards

Chrisb1.