Fiber helps lower cholesterol, control blood sugar and fill you up. Select whole-grain cereals and breads. Be sure to use skim milk. Soymilk and milk products help lower cholesterol, as well as keeping her diet low fat. Low-fat lunchmeats and cheeses are a big help, but also limit your use of butter, margarine and mayonnaise in food preparation.
Exercise is a very effective way to lower blood sugar and cholesterol, and control weight.
Take your daughter for a walk daily, for at least 30 minutes. Perhaps there is an active sport she can enjoy. Distract her from food as entertainment by getting her involved in other hobbies. And, don't ever allow her to eat in front of the television. All meals and snacks at home should be consumed at the table.