Nobody needs reminding about the scary rise in children classified as overweight or obese. Even the First Lady is in on the act. The question is, what do we do about it?

It's unlikely that there's just one single answer. It's a problem that goes across all aspects of our lifestyles, ranging from whether there's safe space outside for children to play, to whether moms and dads have the time and money to cook healthful meals.

But schools are a good place to start when you're looking at children's health. A study from Switzerland looks at the impact of two extra sessions of physical education a week on the fitness and body fat of children ages 7 and 11.

Swiss kids get a legal minimum of three sessions of physical education a week. For the nine-month study, this was upped to five sessions, one a day, plus short 5-minute activity breaks during the day, and 10 minutes of "homework," such as jumping rope or hopping.

Compared with children who'd had the minimum three sessions a week, the kids who'd had more phys ed were less likely to have put on body fat by the end of the study. They also improved more on a fitness test to see how long they could continue running at a fast pace. And they spent more time doing activity deemed "moderate or vigorous."