In many schools gym is not in the budget(s). That is what needs to be mandatory, physical education. That will offset some of the calories that kids are taking in. Their metabolism are high when they are young so it would not take too much physical activity of them to maintain a decent weight. At the same time educate them, don't legislate. It likes Big Brother watching what you eat. Good health is one of my passion and has been most of my life but you can't force people.