Kids need more playtime - and less school Sure enough, the figures brought on a certain amount of tut-tutting and a gratifying shake or two of the head. UCL's Institute of Child Health reports that nearly half of all children are not even getting the recommended minimum of an hour's activity a day, plus a third of children are overweight and this figure is set to rise. But then the evening came around and I sat down to watch Jacques Peretti's excellent BBC2 documentary series The Men Who Made Us Thin, which debated the whole issue of whether obesity matters as much as the diet industry (essentially the food industry) would like us to think it does. There's even doubt as to whether adults with BMIs of 25 to 30 - currently labelled as obese - really do die any younger than their thinner counterparts. I came away wondering if it was so bad that our kids are a bit fatter than they used to be and whether our current anti-fat stance isn't just another way to beat up on the less privileged. And, in any case, isn't it well known that exercise doesn't make much difference? When you run the numbers, it always seems like you have to pretty much climb Everest to work off a doughnut. Plus there's the new neuroscience that says that our body size is governed by the hormones produced in our brains and not by willpower, health education or rates of exercise. Whether you fancy a Ginsters for breakfast or half an avocado is all about how your gut and brain talk to each other. In other words, it's utterly beyond your control - and quite possibly decided in the womb to boot. This isn't to say that exercise doesn't matter. Exercise has all sorts of positive effects - they just don't necessarily include weight loss. Children, of course, aren't in the least bit interested in exercise (have you ever tried to get a child to go for walk? For pleasure? In the country?) - they don't see the point. But children love to run if that means they'll get home quicker. They love to climb almost anything just for the sake of conquering it. They don't want to swim lengths, but they'll haul themselves out of a swimming pool 50 times if that means they can jump in again. And even if we put aside the benefits of exercise to the heart, the muscles, the lungs, the all-important thyroid, there's the simple fact that pumping those young legs and running like the wind is one of the joys of childhood. It's sad if they're not experiencing that. The reasons why children are moving less these days are pretty obvious: cars, computers, cosseting (fear of letting them play on the street). There's also Michael Gove's 2010 axing of the £162m grant for sport in school. What else? Remote controls. In my day we had to get off the sofa to change the channel - but then again there were only three channels. And then there's how 18 years of Labour government painted our cities red with buses (or blue or yellow or green depending where you're from). Growing up in London I regularly shivered at the bus stop for 30 or 40 minutes while waiting to get home from school. That must have burned off a good few Jaffa Cakes. Oh yes, and the current craze for scooters. My son has pretty much grown out of it now, but he hardly walked anywhere for the first six years of his life - and often even refused to push the scooter himself. His favourite thing was to sail along hands-free eating Hula Hoops while I propelled him through the streets. Luckily, he's not overweight - although I'd be lying if I said I hadn't worried about him not getting enough physical play. There's no denying that the activity we call "screens" - as in, "That's enough screens!" - has to be carefully rationed in our house. Of course, everyone at the school gate is pretty fearful about screens. But when I read, as UCL's report states, that children are sedentary for between six and seven hours a day, I can't help thinking: the only place where my child is that sedentary every day is ... the classroom. Of course, school is hardly a new development, but school plus high fructose corn syrup is a new development. Schools plus targets, national curriculums, Ofsted inspections and SATs in Year 2 are a new development. In Germany, children aren't expected to read until they are seven (there's no proven benefit to reading early), and since my son left his playful nursery school, I have often rued the fact that he is spending the most magical years of his childhood hunched over a book or staring at an interactive white board. So maybe we should stop worrying so much about couch potatoes, junk food and the spectre of moral turpitude conjured by those words. Maybe, instead, we should worry more about good old-fashioned school.