Why are children getting fatter? MP Boris Johnson, writing in The Daily Telegraph last week, laments the use of words like "epidemic" to describe the increase in obesity. Johnson, a self-confessed glutton, believes that the more ministers use this sort of language "the more the fatties will think of themselves as victims, and the further we will drift from any concept of personal responsibility".

But as our cover feature shows, overweight children and young people have such a strong sense of personal responsibility for their shape that they hide themselves away in self-disgust. The evidence is that admonishing children to change their diet is counter-productive - most children already know which foods are healthy and which are not. Diets create a misery-inducing cycle of restraint and bingeing.

Now, government is taking steps to improve children's nutrition by providing fruit in schools. New proposals to slap extra taxes on fatty foods are also being considered.

But while diet is important children also need to be encouraged to be more physically active. Sports, dancing and PE lessons at school are important. But we also need to create a culture in which children are encouraged to spend less time at home in front of a screen, and more time out and about using public spaces such as parks. Instead we are suspicious and disapproving of children playing outside if they haven't got an adult in tow. Groups of teenagers can now be dispersed and sent home by the police without any reason. Home, away from the entertaining company of their mates, to the telly, or the PC, with a couple of packets of crisps to cheer them up.