This is just wrong and I've consulted several doctors about it (M.D.s and a PhD nutritionist). Our bodies are made to live off our own fat so long as there is fat there to be used, so while what you said may be true for a person with little spare body fat, it's not true for (e.g.) most americans. As for some systems shutting down, that's part of the point. With the large energy expenditure that digestion requires no longer being needed, it can be "spent" elsewhere, such as autophagy, the using up of dead or unneeded cells to repair other systems.
I have talked to (or at least was present when listening to them talk) literally dozens of people who have fasted for a month or more and none of them experienced any ill health effects. My almost-2-week fast improved my own health more than any other single thing I've done, except for maybe quitting alcohol.
This is just wrong and I've consulted several doctors about it (M.D.s and a PhD nutritionist). Our bodies are made to live off our own fat so long as there is fat there to be used, so while what you said may be true for a person with little spare body fat, it's not true for (e.g.) most americans. As for some systems shutting down, that's part of the point. With the large energy expenditure that digestion requires no longer being needed, it can be "spent" elsewhere, such as autophagy, the using up of dead or unneeded cells to repair other systems.
I have talked to (or at least was present when listening to them talk) literally dozens of people who have fasted for a month or more and none of them experienced any ill health effects. My almost-2-week fast improved my own health more than any other single thing I've done, except for maybe quitting alcohol.
Unfortunately I need to do both again.