+1This site has some good information for adult eating disorder recovery. Home
And the articles on this page could be a good place to start, for both her and you.
Probably important to learn about both the consequences of energy deficiency and the phases of recovery, as well as get support for the emotional issues involved.
It is common for people, both with anorexia and those trying to support them, to get worried about them getting 'overweight'. Remember that anorexia nervosa is much more dangerous than being a bit 'overweight'. She may need help to overcome whatever fears are attached to food for her, and having other people be scared of food and of her eating 'too much' is unlikely to help. She may gain weight - but this is much less dangerous than chronic famine. It is apparently common to overshoot ones natural body weight and then return to it.
Gwyneth Olwyn, who runs that ED institute site, encourages no food restrictions unless severe allergies etc. But if it were me I'd probably pay attention to Peat's information to favour saturated fats over unsaturated ones, and aim to cover all the essential minerals and vitamins daily, as well as eating enough calories regularly.
I think cyproheptadine is sometimes used specifically to help restore appetite for people struggling with anorexia. It can also help make sleep easier for some people. Even quite small doses (eg 1/2 mg) can make a difference for some people; others have used more.cyproheptadine
It has some anti-serotonin effects, so it won't work the same way as SSRI. Consider reading Peat's article (on his website) on serotonin to see why this may potentially be a benefit. Coming off an SSTI needs to be done carefully, though, I think.
Getting enough minerals could well be important.she needs electrolytes/minerals asap! instead of purging have her take cascara sagrada.
I agree that purging is a dangerous habit. But I would not encourage regular use of too much cascara sagrada - that could also become a dangerous habit. Just eating enough food regularly is likely to improve transit speed soon - famine tends to slow transit by a couple of mechanisms. Possibly a small amount occasionally could be useful if needed, but just minimal.
I agree that vomiting is dangerous, but she is not overeating, she needs to keep the food inside her long enough to digest it and use it, not lose all that nutrition she needs. If she has AN, then recovery - which means eating and retaining nutrition consistently - needs to be a high priority. That doesn't just mean 'normal weight', it means reliably eating enough to sustain a healthy metabolism and grow to maturity. According to Gwyneth's investigations, documented on her site, that takes about 3000 cals for a young woman in early 20s, unless she's exceptionally short or tall. For someone recovering from AN, that's a minimum guide, but hunger may say to eat more to make up the deficit some times.she still needs a way to get rid of the food she overate or she won't be able to function or think about anything else