It would bother me if the comments were unsolicited (like if you hadn't given any indication that your weight was something you wanted to discuss).
The obvious response is to suggest that you talk to her about how it makes you feel, but I know it's easier said than done.

I took it kind of personally when I was talking to my therapist about my ED and I'm at a "medically healthy" weight and he thinks I shouldn't be trying to lose weight, but when I was saying the negative feelings I have about my body he asked about/suggested exercise, and that felt like he was agreeing that I should change something about my body but just thought that given my history it would be a bad idea for me to start restricting again