Mariella Frostrup: Children aren't obese just for the heck of it, but because many low-income families survive on a diet that went out of fashion in the late Seventies.
Kids' exercise levels are even more abysmal than we feared. And, says Peta Bee the repercussions are not just physical - they extend to academic achievement and social behaviour. So what can we do to get them off the sofa?
Commercials for junk food are being banned on children's television, but advertisers are moving onto a new battlefield - the internet. Helen Pidd reports.