Couple things: 1) The plate lunches photographed exceed the calorie intake per meal that high schoolers should get, much less kindergarteners.  I think the 15% of overweight high schoolers is off.  They use BMI, which isn't as good as using a body-fat index, and I wonder how well the measuring is done.  My guess is it's closer to 20-25%.  
2) In any event' that's not the only thing they eat.  The school still has vending machines with sugary drinks, which is one the key components to childhood obesity.  So it's about money and special interests and not childrens' health. Lots of hypocrisy there.
3) Due to Abercrombie cutting dental care for poor people, and I've failing to reinstate it, both the children, and the parents who decide what's for dinner, may not have teeth good enough to eat the veggies and fruits.  For instance, the picture showed apple and pineapple slices

Thanks for the interesting article! :).