You bet this is a problem and one the mental health professionals in the frum community are really worried about. After all, anorexia can kill – literally. When the person falls below a certain percentage of their normal weight their body chemistry goes haywire. Nineteen year old girls can die of heart attacks. I think the mortality rate for cases where treatment doesn’t work is something like 1 in 5.
Part of the problem is an issue of control, part of the problem is our mania for size 2 girs in shidduchim.Whatever the cause, there are a lot of young people at risk. If you have a problem, ask your rav to recommend a professional. If you have a friend with a problem, try to talk them into going for help. It can be a matter of life and death.