Hi MarieLynn You can't stop your daughter from trying to lose weight and it is almost impossible to convince her that she doesn't need to lose weight (I know this cos my mum is always telling me I don't need to lose weight but I think I do) What you can do is make sure she knows that to diet isn't the good thing to do but to eat a healthy diet is good. There is a difference here. To diet is to cut back on foods with the intention of losing weight. To eat a healthy diet is to ensure that you are eating a balanced diet with the correct nutrients to ensure the best health possible, and be eating healthily your daughter may lose weight. You could suggest to your daughter finding out about good nutrition and work together to try and ensure that you both are eating healthily. In my opinion this would work better than telling her not to diet and that she doesn't need to lose weight. If she is like a lot of teenagers (and I'm by no means saying that we are all like this) if somebody forbids her to do something she will be resentful of that and go out of her way to prove you wrong and that she can still lose weight when told not to. She should be eating 3 meals a day, plus 8 glasses of water and if she is still hungry she should snack on fruit, carrot/celery sticks or low fat crackers. She should try to eat at least 5 portions of fruit and veg each day and stick to foods that have less than 5grams of fat per serving in them.