People who watched more weekend TV as kids are more likely to be obese as grownups, a new study from the UK shows.

The findings add to a growing body of evidence linking time spent in front of the tube to excess weight. Several factors may be responsible, the researchers note in The Journal of Pediatrics. TV watching replaces time that could be spent being physically active, kids who watch more TV see more ads for unhealthy foods, and kids may munch junk food while watching.

In the current study, Dr. Russell M. Viner of Middlesex Hospital in London and Dr. Tim J. Cole of University College London set out to determine whether the timing and type of TV watching, as well as mothers’ attitudes toward television, would have any effect on adult weight. They analyzed a group of more than 11,200 British men and women born in 1970 who were followed up at ages 5, 10 and 30.

Every additional hour of weekend TV watched at age 5 increased the likelihood of obesity at age 30 by 7 percent, the researchers found. There was no connection between adult obesity and mothers’ attitudes toward TV, weekday TV watching, or the type of programming watched.

Viner and Cole point out that their study addressed TV watching in 1975, when the UK had only three TV channels. Only one carried advertising, which at the time “was relatively unsophisticated and limited.” This suggests, they conclude, that the effect of TV watching seen in their study is likely due to its displacement of physical activity, rather than any effect of food advertising.

In another study published in the same journal, Dr. Kirsten K. Davison of the State University of New York at Albany and colleagues found that parents’ own TV viewing habits had a major effect on how much TV their children watched.

Their survey of 173 girls aged 9 to 11 found that 40 percent exceeded the American Academy of Pediatrics’ recommended limit of two hours a day. Girls whose parents watched a lot of TV themselves, as well as those who relied heavily on TV as a recreational activity and spent more time watching TV as a family, were more likely to exceed the limit. Not surprisingly, girls whose parents did not limit their TV viewing tended to watch more.

In an editorial accompanying the study, Dr. Reginald Washington of the University of Colorado School of Medicine in Lone Tree points out that excessive parental TV viewing may be setting children up for a lifetime of doing the same. “They are, in a sense, learning that TV is not only a normal part of life, but it is their chief form of recreation.”

As Davison and her team write, “Children can learn to choose and prefer activities other than TV viewing, playing video games and using the computer. The challenge is to provide guidance and support for parents that will promote this objective.” They cite one helpful resource, the TV Turnoff Network (http://www.tvturnoff.org).

SOURCE: The Journal of Pediatrics, October 2005.