I don't think it's just preservatives that are an issue either, its food that is 'empty calories' as well that don't fill them up enough. Also not with my kids, but with BIL's boy he used to go crazy after having fruit and all he would eat all day was fruit and his behaviour was uncontrollable, but when I said something about it to MIL and to cut the fruit back while she had him (she was looking after him 2 days a week) she noticed a difference. His behaviour is still uncontrollable but not to the extent that it was.