My 15 year old daughter is anorexic, but she refuses to admit it.?

How do I get her to see that she has a disease? She is an elite gymnast and trains constantly. Her coach has approached me and even some of her teamates. I don't want to embarrass her, but I don't want it to get worse. Her boyfriend is also an elite and he is 17; he's noticed it as well. She has incredible trust and faith in him; he has helped her work back from a terrible injury and says she wouldn't be back in action and winning she didn't have him. Should I get him to talk to her? Thanks.