How do I convince my friend she is losing weight the wrong way?

My best friend is trying to lose 40 pounds. So am I. I try to eat healthy, nutritional foods. I don’t count calories, i just make sure to watch fat and sugar intake. I usually have 1 or 2 salads a day and a healthy breakfast. I try to work out for an hour-an hour and half every day. I think this is the healthy way to go about it.
My best friend is drinking coffee and vitamin water for breakfast, eating very small lunches with no nutrition in them, and she only eats supper because her parents make her. She works out 2–3 hours a day and constantly talks about wanting to throw up her food if she ate too many calories. I’m really worried about her. Any suggestions on how I can get her to try to lose weight in a healthier way?