As a high school teacher for 37 years, who had a number of eating-disordered students--I would just like to echo the advice to get professional help as soon as possible.
It's hard to understand how disordered the thinking of an eating-disordered sufferer is until you see it close up. I had girls, who were very bright and were still doing excellent academic work, refer to food as "their enemy" and who thought they were fat, when they more closely resembled concentration camp survivors.
I see the comments suggesting that the home situation is always at fault. My experience was that there were many different triggers--culture and peer group being major ones. I think there may also be something bio-chemical going on, although I'm not a doctor or a scientist.
At any rate, I would certainly would not blame parents, who are always devastated by this illness in their children--anymore than we now blame parents for autism.