It does seem like a lot, doesn't it? The evidence looking into green tea (that I've read about at least) says it doesn't have any significant effect on appetite or weight loss (though can have health benefits), so I'm not really worried about whether drinking it a lot would hurt her physically. But there is that common belief that it helps with weight loss so if she thinks that and that's why she's drinking it that is worrying, like you said!! I hope she continues with therapy too if she needs it