A new study on young adults’ use of digital technology finds that the more hours spent per day in front of a screen are linked to less time spent exercising and less healthy body weight. But the results were mixed, as decreasing screen time for some adolescents did not correlate with more exercise and healthier body weight.
Studies have established a link between time spent watching computer or TV screens and a rise in childhood and adolescent obesity, a result which has physicians and parents concerned about how to curb the urge towards sedentary behaviour amongst children. A five-hour-a-day TV habit, for example, increases the odds of childhood obesity by 78 per cent, according to one study in the Journal of Pediatrics, which found that 7.8 per cent of youth surveyed watch five or more hours of TV a day.
Now, a study from the Infinitas Research Group, based in London, Ontario, published in the International Journal of Adolescent Medicine and Health finds that although less screen time and more exercise seems to translate into healthier body weight for some young adults, the relationship doesn’t hold for all of them.
The results come from an online survey of young adults the majority of whom were between the ages of 18 and 22. Responses from the 262 participants were analyzed according to the amount of screen time per day, the amount of exercise per week and body-mass index (BMI), a common referent for health —a BMI of between 25 and 30, for example, is classified as overweight, while a BMI higher than 30 is regarded as obese.
The study results showed that among respondents who spent less than four hours per week exercising, higher screen time (more than five hours per day) correlated with a higher BMI — 23.8 for more than five hours per day compared with a BMI of 21.8 for those watching less than five hours a day.
Yet for those young adults who exercised more than four hours a week, there was no correlation between screen time and BMI. Further, no link was found between hours of exercise and BMI for young adults who spent less than five hours per day on screens.
“Healthy lifestyle choices such as fewer screen time hours and more exercise can be beneficial to young adults,” says the study’s author, Ronald Chow. “Among certain groups, such as those who spend a lot of time on screens and those who do not exercise regularly, the benefits of more exercise and less screen time, respectively, are much more noticeable.”
All screen time is not created equal, however, according to a study in the journal Pediatrics, which found that using smartphones, tablets and computer screens is less of a factor in childhood obesity than TV watching. The study found that 14-year-old boys who paid the most attention to what’s on TV weighed on average 14.2 lbs (6.4 kg) more than boys who reported paying the least attention to TV. For girls, the difference was 13.5 lbs (6.1 kg).
Why is TV so problematic? The boob tube combines two detrimental things: exposure to ads that push high-calorie snack and junk foods and, unlike the more interactive time spent on a computer, watching TV leaves one’s hands free to snack to one’s heart’s content.