I don't think kids can learn to delay gratification at that age. I think it's still a parents job to regulate what they eat. I try to really limit the junk that I buy. If we don't have it in the hosue, it's not an issue. But, there are a few things that my husband loves, oreos, little debbies. And then there's all that Haloween candy. I have a system. I have an upper cabinet. On the bottom level there is granola bars, raisins, saltine crackers, dried apricots, cereal bars, peanut butter, etc. All the stuff I don't mind them having. The next higher shelf I have the worst offenders cheezits, oreos, candy. My kids can't really see what's up there. If we walk over to the cabinet they can see the good shelf. They have to really earn something off the next shelf. It's the same way in the fridge. Lower levels have the fruit, yogurt, string cheese. You have to go to the top of the fridge to see if there are maybe some cupcakes or something. Theres a fruit basket on the table full of apples and bananas. I also negotiate the bad stuff. If they ask for cookies I tell them ok, 2 cookies, but yogurt 1st. Or pickup all your toys and then 1 cupcake. I do the bulk thing too and it works for us. I buy a family size bag of chips and portion into 10 ziploc bags and hide them. That way I can send chips with my husbands sandwhich everyday. I portion the cheezits, dried cereal to snack on, pretzels, etc. I make my own little 100 calorie packs for me and the kids so I know we dont sit down with the whole box of something and mow it down without even realizing it.