I'm overweight, I know I am, but I am happy in myself - I'm not as big as your friend but I know I could do with going down a couple of dress sizes. I'm afraid if someone - however well-meaning, unless it was my doctor - told me I needed to lose weight, I would tell them it's my business, and to butt out. If's she happy then she will only lose weight when she has the incentive herself - other people's perceptions really don't help. I would, therefore, suggestion you don't do anything, she's an adult and she knows the risks of being a large lady.