My advice is get a new Dietitian if you can. All Dietitians have to learn about eating disorders. That does not mean they treat them though. I would ask her how many clients she has with your diagnosis parameters. I have had both kinds of Dietitians and now because I have an ED one my therapist does therapy. My D works very closely with them and my Doctor's. If you have a treatment center in your area they can be good resources for eating disorder specialists. My D would never recommend exercising with a borderline BMI. that could be dangerous I would think.