What's really needed is a societal change with how food is treated. Someone else mentioned a tax on sugar and processed foods, which could help. But another big step would be trying to teach students about nutritious food and living a healthy lifestyle. Of course, it's difficult if the school is the only place they see this, but I don't think it would hurt to have more outlets for healthy living in a student's life.
[1] https://en.wikipedia.org/wiki/Military_budget_of_the_United_... [2] https://www.cbo.gov/publication/50737 [3] http://markbittman.com/health-vs-profits-in-school-lunches/