what you said: You look great! (with a gesture towards her body)
what she heard: Oh my gosh! I have gained a million pounds and they think I look chunky now!
what you said: WOW, have you been working out lately?
what she heard: Nice job on the weight loss, keep starving! It's paying.
what you said: I wish I could be tiny like you!
what she heard: You better not gain weight or no one will want to be like you anymore. No one likes a fat girl.
what you said: I need to drop a few of these pounds! My hips are huge!
what she heard: You need to drop a few more pounds! Your hips are huge!
what you said: I finally dropped my baby weight plus some!
what she heard: You could stand to shed a few pounds yourself.
what you said: I don't eat _______ kind of food, it makes me bloated/gain weight/against my diet
what she heard: You shouldn't eat.
what you said: have you lost weight again?
what she heard: I don't think that you have really have lost weight? You still look bigger to me.
what you said: Aren't you going to eat?
what she heard: I can't believe I have to deal with your garbage AGAIN. Can't you just get over yourself and quit making me uncomfortable around you?
It doesn't make sense. It isn't rational. That is the disorder of it. Your intentions are good, she is just hearing you through orange colored hearing aids. The disorder takes priority over all else. If you could rationalize it, she wouldn't have a problem and you wouldn't need to rationalize it.
Small things trigger her, and you don't even mean to. Things like new health food kicks, how long you spent at the gym, how much weight you have lost by running, your disgust/unappreciation of your own body, or saying your actual weight or your desired weight. To you it is random conversation, to her, it is an obsession of body image. She won't hear what you really say and that is not your fault, it is the disorders fault.
This wasn't a post to scare you away from talking to someone with an eating disorder. It was a post to help you understand a little bit of what goes on inside her brain while you are talking to her. Keep talking, she needs to know she is worth knowing.