Hi Welcome to HCM
I have gone through your query . .I Can understand your concern about your daughter's condition due to anorexia .

Anorexia nervosa is a serious life-threatening illness that typically has its onset during the adolescent years . This is the age when child doesn't know good or bad for her & thinks self , know-All .

Here becomes the duty of parents to treat her psychologically , apply interpersonal psychotherapy, recreation, art or music therapy, nutrition .
Her physician can be taken into confidence so that she be made to understand clearly that Her weight is too low as per her height and can lead to some serious medical trouble , needs medical attention & physical health and weight restoration are not negotiable .

When psychological factors are involved, creating a happy and calm atmosphere helps to improve the condition. Being in the company of good friends and relatives relieves stress and improves digestive power.

Get her checked up thoroughly . so that proper treatment can be given to her if need be .

You can try some home remedies ...

Ask her to take lemon juice with a glass of water and salt and sugar .
Take coconut water and its pulp .
Make a mixture of extract of lemon ,ginger , garlic coconut water bark of mooringa tree and honey . Give her 25 ml with equal water ,before meals .
It is a great appitiser and excellent antioxident

Meals should be freshly prepared ,according to her taste , but nutritious.

She should be guided to some walk , yoga / pranayam , so that her digestive system works properly , to let her lead a healthy life

Hope it helps you solve your query . Take care All the best . Wish her all the best .
Don't hesitate to get back if have any for further query .

Thanks for the query.
This is the side effect of busy sheduled life. Nutrients defficient food. No problem you can help her with protein powder. I suggest a high protein drink twice daily. You can see the result within 2 weeks.