Banning stuff is a bad move it sends the wrong message.
People don't understand the 'everything in moderation' mantra, or the fact that calorific intake has to be less or equal to output, depending on whether you are trying to stay a certain weight or lose it.
I tell my kids that you have to make sure you are doing PLENTY of exercise if you want to eat whatever you want.
We're out and about walking for at least 2hrs a day and they watch a max. of 1hr telly a day.
I am one of six siblings none of whom are overweight and all of whom take part in regular exercise. When we were young we were told being over weight is very bad for your health, we did, however, eat cake, sweets and biscuits and continue to do so.