The federal government should stay out of the catering business. Local school districts are better at it.
What each school needs is a lunch lady standing at the place you deposit your tray. Our lunch ladies were big scary women who examined the contents of your tray and told you if you were finished or not. If she said eat more of your vegetables that there are children starving in China who would eat those vegetables, while she waved that huge metal spoon at you, you went back to your table and ate more of your vegetables.