Never posted to you before, but often read your threads...
I, too, was an anorexic at about the same age as your daughter is now. I got down to 75 lbs...nobody knew what it was back then. My periods stopped and it took a few years of BCP's to get them back.
My anorexia started when we moved from one city to another during my 8th grade school year....I was a popular cheerleader with lots of friends, and I was uprooted and moved off for my mom's job (she was a single parent)... I now know looking back on it that this was my way of CONTROLLING something in my life...
Also, as a side note, it is believed that OCD and Anorexia are different manisfestations of the same disease...and lo and behold, I did also develop OCD in my 30's..( I am 42 now)...yuck. I control it now with anti-depressants.
Is there something in your daughter's life that she feels out of control of???either overt or hidden?
Hope she gets well soon...it is a dark place to be in.