This worries me too.

We plan to use other things as 'reward' for good behavior etc, ie a trip to the beach. If there's one thing I don't want to do, it's to set up a bad association with food, ie you've been naughty, no dessert for you etc.

I will have the biggest battle with my mil, who likes to offer all her grandkids ice-cream every time they walk in the door to be the favorite grandma! It's going to cause big probs.