Parents of healthy, regularly active children should not ban junk food from their child's diet.
Donuts: not only a sweet treat, but a source of quick energy. Donuts are a simple sugar and our body can't tell the difference between sugar from donuts and sugar from fruit. Simple sugar shouldn't be the basis of the meal, but an addition to it.
Children can always access foods that are banned at home, at school.
Consumption of junk food will not immediately result in obesity. Yes, prolonged eating of foods with saturated fats and high sugar content will result in health issues over time. Staying engaged in physical activity will help decrease the risk of health problems caused by being sedentary.
Balance and moderation is the key to getting adequate nutrients. Having a diet that consists of either all fruits or all junk food are equally as detrimental to the human body.