She must be comparing herself to others at school and believing her worth has to do with her looks or weight. Maybe model healthy eating all together, trail mix, salads, fruits etc. But slowly and maybe she can also go to a therapist herself, or as a family
“She has dreams to be an envy, so she's starving You know, covergirls eat nothing She says beauty is pain and there's beauty in everything What's a little bit of hunger? I could go a little while longer, she fades away”
Ask her about details. Like why is she doing it? Does she have a goal weight? What will she do if she reaches that weight? Also try to encourage other foods as well even if it is not much. Cheese is a good one and has keep humanity alive for thousands of years. Maybe she is only doing a dairy thing after all. Also make sure to gage how they view their body image. And try to set challenges for them. Like have them find plus size or disabled or other unconventional type models. Surround them with body positivity. And get them a support network. Of their own peers as they will be most effective but also therapy might help as well. In the mind of someone with an eating disorder is a fear and shame of not liking your physical form. So having others accept her as is is a way to fight it. And you have to keep it up until they can see it in themselves. But a long hard road there:(
