I taught high school English for 35 years, and had many discussions with my students about food. They loved debating topics like fast food, best/worst coffee shops, etc.
My takeaway from that, and from my experience growing up and with my own children, is that banning certain foods can make them more desirable. The kids who seemed to have the healthiest attitudes were those who were allowed to eat junk food but were also served plenty of good food. That's what my parents did, and what we tried to do with our children.
I remember my youngest daughter wanted to bring strips of sweet red or yellow peppers for her school snack. I would have been happy giving her cookies, since they were so much cheaper, and we had no money then. But we found the money. And I think now that if we had pushed the peppers she probably would have wanted the cookies.
Fresh food just tastes so much better that I think if we resist labeling certain foods as "good" or "bad" our children will migrate to the healthy food.