Yeah, you don't normally experience the thinning during a 30 day fast. I remember the first time it happen to me. I actually thought it was the shampoo I was using because I had just switched shampoos. I called the company, sent back the shampoo and got my money back! But I kept losing hair.
So, then I went on a wild search for any information I could find on why I might be losing hair. Then, I came across it in one of my juice fasting resources, that long term fasts (over 40 days) could and most likely will lead to hair loss/thinning. It had to do with the lack of protein or oil intake. I'll have to look through my books and see where I found that info.
Sure enough after I stopped fasting my hair started to grow back, full force. I had new hair amongst all my older long hair. It was crazy. It was nice too because years before I had almost melted my hair off, experimenting with professional dye. I think I had actually destroyed hair folicles because my hair never grew back normal, until after this fast. Now, I have a healthy, strong head of hair, even with me dye/weaving it every 4 months.
My hair has started, in the last couple of weeks, to thin again. It's scary but at least I know what's going on.
Oh, and I remember reading that if you're concerned about the hair loss that you should stop fasting for a week or two and start over again. This will help stop or slow the thinning process.