Thanks a lot! Well, during the fast I passed urine regularly but in really small amounts, from day one, and now after 5l of water over two days there's still not much coming out (compared to normally.) Does that mean my body is trying to spare electrolytes?
By milk, you mean cow's milk or any other milk of animal origin, I suppose?
In light of your comments and links, the refeeding as suggested in my first comment does seem to make sense, as those foods are very low to zero in Sugar and do contain the minerals you suggest.
I am indeed feeling a bit off. So I might change my strategy according to your recommendations. I'm really surprised though, since supposedly those Russians have the most experience with dry fasting, are the only ones to have done it clinically, and from what I had read they said it's important to first re-hydrate with plain water, as the body would not be able to digest anything else in a dehydrated state.
Milk would require some effort to digest, while coconut water contains sugar...