I think I might be very much a minority opinion on this one, but I do think people get too hung up on the healthy diet 'no sweet' rule thing, to the point that I know quite a few weight obsessed people, who have in turn, inflicted their 'obsession' on their kids. As children, I was pretty much given free reign on what we could have, and I have always eaten what I want, when I want, and I don't really think about it. I have always been thin, and so have my siblings. And equally, I am mid 40's and have never had a filling. I do likewise with my children, if they want a chocolate bar, they can have it. Not having set times, or treating them as 'special treats', reduces the magical appeal, somehow. Some days they don't want any, but when they do, they have one! It is better to allow ourselves to be guided by appetite and self-awareness, rather than have somebody impose restrictions on our behalf. My daughter had a friend who was very overweight, as was her mother, and they all lived by a strict no-sweets, carrots in the lunch box rule. And one day when she came to our house, she scoffed an entire box of chocolate rolls, devouring them like she hadn't eaten for a month. My daughter was shocked, she eats chocolate when she wants, and because she can, she has no desire to sneak a bar or twelve when nobody is looking!
Moderation is my motto. The more you can't have something, the more it is wanted.