Have you looked into going to family therapy? Or getting a nutritionist for her?

I have heard of orphans doing the same things as she is once they are adopted. My friend, being an orphan, went through that phase until she was 3-4. She became very chubby, but lost it as soon as she started school. I even had a phase for a while where I would binge eat 1000s of calories as a kid because of neglect when I was 3. I would eat as much as I possibly could as I was scared I wouldn't get anymore. It took a while to get out of the habit but around 10, I started eating more normal. Thankfully, I was extremely active so my body needed all the food I scarfed down, but my mentality behind food wasn't good.

I would give her time. Maybe show her where the food and juice is and give her an option of what she can eat at a certain time. Like show her a cup of green beans and a cup of carrots and let her choose. Same with juice. That might help her realize that the food isn't going away. I would also get her on children's vitamins if you haven't already. For me, going on vitamins really helped.

I am not a professional, so I am going off of experience, so definitely look into therapy for her. Even at this age, it will help.

Good luck, I hope everything goes well.