further to my first post in answer to those inaccurate websites, these are the actual figures for loss of tissue as published by Yeo's Physiology during fasting and even in starvation................
The losses and changes which occur during the fast. In death by starvation the following losses have been observed by some investigators:
Chossat's table was made from animal experimentation, and agrees very well with the observations of others, except in the loss of blood. Others have given this as less than twenty per cent. The International Encyclopedia, under "fasting," gives a table showing the losses sustained by an animal while fasting for thirteen days. This table gives the loss of blood for this time as 17%. and the loss to the brain and nerves as none.
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.
Of course there can be very rapid gains in weight post-fast, but that will depend entirely on the quality, quantity, and type of food that is eaten. If your post-fast diet is very high in carbohydrates such as rumbabas and other equally obnoxious processed foodstuffs, then weight gain will be mostly fat, but if the post-fast diet consists of unprocessed organic fayre, the resultant gain in weight will be healthy tissue and NOT predominantly fat.
The irresponsibility of authors such as those you have quoted and the erroneous and misleading information they give out, makes my blood boil.
Whoops! I'd better watch my BP in case I have an embolism.
It was also claimed that fasting causes dehydration even while drinking water; this is complete nonsense; does anyone suffer from dehydration while eating if they are taking adequate fluids? then why should it do so in any other state of inanition if adequate fluids are taken??
I hope this has answered, for everyone here, at least some of the questions regarding fat loss and weight loss while fasting.