Sadly, far too many parents end up locked in just this type of defeatist paradigm when they're trying to deal with junk — attempting to deny their child's yearning, and place absolute restrictions on their access, without comprehensible justifications or lessons. This often ends up backfiring for a few reasons:
1) Kids love a fight, as it provides them an opportunity and template for engagement.
2) Unqualified limitations create a countervailing, and often stronger, desire for transgression.
3) Enforcing limits without providing tactics for confronting the underlying desires hampers kids' ability to make intelligent, informed decisions.
Your goal, therefore — as with most things with young children — should not be to attempt to completely quash this profound inclination, but to teach your kids how to deal with it in a way that fosters a healthy, lifelong relationship.
This is not to say that you shouldn't have rules. You should. You can even have ones that place off-limits specific categories of, or locations for consuming, junk: only buying foods whose colors exist in nature; only eating bacon at Grandma's; only watching Caillou when Mom is out of the room. They should just be proactive, logical, proscribed and realistic.
Rules should just be proactive, logical, proscribed and realistic.
The goal here is, instead of creating unconditional and unachievable rules, to form functional ones based on kids' innate desire for structure, consistency, and independence. I therefore suggest what I call the Co-Option Option (COO)? The COO works like this: instead of engaging in immature, futile, and degrading head-to-head battles with your young child about things you can't wholly control, and aren't, objectively, all that important — splashing in the bathtub, playing with food while consuming it, watching the occasional episode of Boohbah — you take the fight out of the situation by redefining it so that you are in charge, while also offering your child the sense that they're getting what they want.
For the tub, the COO would work like this. Instead of constantly trying to preclude your child's desire to splash (in a room which is, by design, fully waterproof) you tell them they are allowed to wallow to their heart's content for the first and last two minutes of their bath, but need to cooperate during the middle portion when you're helping them get clean. You provide clear indications of when their water-play period begins and ends, complete with markers (One more minute.) And you have repercussions — connected to the situation, and laid-out clearly and in advance — if they don't conform (removal of a favorite bath toy).
For junk, it's pretty much the same drill. Make clear protocols about when and in what amounts treats like candy, snacks, and television can be consumed; provide indications of clear and actionable repercussions if these protocols are not followed; and then simply stick to what you say. If kids know that dessert comes only on weekends, that they can watch fifteen minutes of Dora as soon as they get home from preschool, or that they can eat their fill of Cheetos when they visit their Gay Uncle — and that these are the only times that such things are generally allowed — they'll be much more likely to understand that these are controlled substances/"treats," and much less likely to ask for them on occasions when these requirements aren't met, and much more likely to learn the balance and abstemiousness that will help prevent them from becoming obese couch potato diabetics later in life.
