Under the new rules proposed Friday by the Department of Agriculture, school vending machines that once were full of Skittles and Sprite would instead be selling water, lower-calorie sports drinks, diet sodas and baked chips. Lunch rooms that now sell fatty "a la carte" items like mozzarella sticks and nachos would have to transition to healthier pizzas, fruit cups and yogurt.

The rules, required under a child nutrition law passed by Congress in 2010, are an effort to combat childhood obesity. While many schools have already made improvements, others are still selling high-fat, high-calorie foods.