About the skin...
I read that you do not get flabby skin fasting.
I have yet to read where that has happened and some of these ladies have lost quite a bit of weight.
About the BMs...(yummy topic, I know)
It seems the body expels anything left over in your intestines before the fast, but then they start to slow way down when you get into the fast.
It is recommended that you either do a salt water flush (I did one and it was awful), or you buy Senna tea...it's a laxative tea (don't over do it), or do enemas.
The toxins will sit in your bowels and this is very bad for you. I personally am going for the tea. I read that people take some at night and the next day your bowels move without cramping.
I hope this has helped you!
Good luck with your fast.