If you want to stop childhood obesity why not start by putting recess back in to the elementary school day? That’s an hour a day of exercise that children don’t get any longer. Fifteen minutes each in the morning and the afternoon and thirty minutes at lunch. The teachers spend at least that much time in a day fussing at the kids because they can’t sit still. If I were a teacher MY class would have recess! Purely in self-defense. I’m just saying.
While I’m on the subject…….we have about five sidewalks in our town. If a kid wants to walk anywhere here they have to do it on the side of the road or through someone’s yard. I’m talking about in town, no sidewalks! Who wants their child to walk through downtown traffic in order to get to the park or the recreation areas?
If we want to have healthier children in America we need to facilitate their access to healthy environments. We can’t remove every healthy activity from their lives and then wonder why they are obese.
Thought For Food 
I agree, Anna. My granddaughter got her arm broken by some boys who were bullying her in the school yard. And yet, I would rather she have the time to decompress. Elementary school aged children just don’t have the self control to sit still for hours on end in a classroom. They will be doing that for the rest of their lives at work. When do they get to be kids???
Don’t forget, schools are now mandated to teach extra topics, like baloney about the USDA food pyramid “Mom, why do we have whole milk and butter when the teacher says they aren’t healthy?”), so the pressure to forgo recess is strong from a time standpoint. Add to that the issues of injuries, bullying, and need for supervision during recess, and you have a strong motivation for schools to eliminate it.