I have one child who is overweight and another who is thin. so, what do i cook for dinner?

Not a problem: Cook healthy. The thin one will love it and not notice the difference. The overweight one will learn good habits. Make balanced meals that are heavy on fruit and vegetables. Avoid convenience foods, fast foods, and junk foods. No hot dogs and burgers! allow limited desserts on weekends only, dinner only. Provide nutritious snacks like non-fat yogurt and fruit anytime. Reward good habits.