My parents have been pestering me...?

They've been a really big pain in the . They have been nagging about how I don't each so much anymore, how I skip meals sometimes, and the fact that my weight keeps dropping. I personally don't see what their problem is. For the record I do have an eating disorder (my parents don't know), but why should it be their problem? My dad has always been the one to tell me to lose weight because I was too fat. Well I lost a lot of weight and all I want is to lose 20 more kg's, why should they care? I'm just doing everyone a favor. They just don't see things the way that I do. I am happy with the loss, yet they aren't. Any way I can get them off my case?