This has already happened in the UK. Last year, a tv show hosted by jamie Oliver (a celebrity chef) highlighted the poor nutrition in school canteen meals. The worrying fact was that 3 times as much government money was invested in the nutrition afforded prison inmates than children in school per meal
Things have now began to change, with a national ruling on what should be offered in school canteens, and funding adjusted accordingly.
The only fear I have is that the rulings will have the opposite effect to their intentions, and that kids will come to see indulgence in 'junk' food as yet another form of rebellion, along with smoking, drugs and alcohol.
Removal of choice does not lead to the removal of the problem. An increase in 'nanny state' politics is never good IMO. Where will this end- good ol' boys running burgers across state lines? Speakeasy's selling candy to shifty characters in the dead of night?
The atttitudes of a free society can only be changed through education, enforcement, no matter how benevolent sets a dangerous precident.