Re: water VS fat loss?
The "lots of our weight loss is water" statement isn't exactly true. It depends on how long you fast, how much your body needs to lose and how much water weight you naturally carry. A short fast, of 1 to 10 days will be mostly water weight loss. Any longer and you're delving into age-old fecal matter, fat, and dead/diseased/dying cells.
If you're at a normal weight, you will most likely not lose any fat in a 10 fast. My cousin for instance, 5'2" & 110, will fast for 10 days, drop 5
pounds and promptly gain it back after the fast. It was water/fecal weight.
Someone who's extremely overweight can lose a pound a day, or more.
And as mentioned, water weight retention is also a factor. I posted a story, some time back about a guy who had a disease that made him retain massive amounts of water. He fasted 30 days and dropped 100 pounds. Most of it was water/fecal, and I'm sure some fat.
I don't think there's a "point" that you start losing. It all depends on your body.