You should come to Ireland and see how many of our schools ban junk foods.
Junk foods and sweets get quickly confiscated at entrance.
Our government had pulled out sweets' vending machines from schools, after a 3 year old child had died of a heart attack due to obesity. Lots of kids were becoming obese, so our government had to do something. Today, we don't see as many fat kids as there were before.
Here is something else. Our local schools have seen vast improvement in the behaviour of pupils since the ban of junk food. Sugary foods make kids hyper-active or moody.
As parents are being too busy to pack school lunches for kids, many companies are manufacturing healthy food packs for school kids and selling them in shops.
Another thing, some of our schools are doing breakfast clubs, as there are many kids going to school hungry. As result, well-fed kids concentrate better on studies.
My niece is 13. She is conscious about healthy eating, which she has learned first at primary and later at secondary schools. 5 years ago, I once tried bribing her with sweets and she refused them, saying that they were very bad for health.