Researchers compared the TV viewing habits of more than 6,000 British people born in a single week in 1970, at the ages of 10 and 42. Parents should increase children's physical activity to ensure they become fit and healthy adults, the University College London (UCL) authors conclude. ‘Do something active to displace TV,’ advised co-author Lee Smith. ‘In the evening time when families tend to sit down and watch TV they should try to go for walks instead.’ If you can't go outside, try active computer games, anything that gets people up and expending energy rather than sitting down and snacking,’ said Dr Smith, of the UCL epidemiology and public health department. The authors acknowledge that for today's children TV viewing is often replaced by time on computers, smartphones or tablets. Parents should play active computer games with their children, say researchers.