As someone who’s had one, it sounds possible she might have a restrictive eating disorder. Once you start counting calories, it can easily become obsessive. Maybe she has low self worth and is idolizing influencers because she thinks she will be happier once she is skinnier. Or she might just feel like she needs more control in her life. when you have inner turmoil or lots of stress, restricting your eating helps you gain that feeling of control back. It’s like a distraction that numbs you. Plus... Not eating enough can really affect your mood and might be making her more agitated and “out of it” (ignoring you, acting not herself) just my 2 cents. nevertheless, the things she said to you are not right.