The problem with the protein shake is it’s 400 calories in liquid form! So I doubt that’s keeping her full for long even if it’s protein. She’ll be secret snacking for sure. I think this is the root of her weight gain. She takes in a lot of calories through liquid without realising it. Protein powder is good for building muscle, there’s absolutely no need to take it if you’re not lifting heavy weights. Fruit and high protein Greek yogurt would benefit her more.