In our modern world, TVs, laptops, tablet and mobile phones are part of everyday life. Childhood obesity is on the rise. Latest figures show 15% of children in England are obese. Could this be due to increased time spent in front of a screen?
About the study
The study, which was published in the International Journal of Obesity, analysed data from the Millenium Cohort Study. This longitudinal study followed 12,556 children from the age of 7 to 11 years. They aimed to look at the association between “screen based media” and body weight. Researchers examined the number of hours spent watching TV, DVDs or playing on the computer. They also noted whether the children had a TV in their bedroom.
Three methods were then used to analyse the children’s body weight. These were their body mass index (BMI), fat mass index (FMI) and the specific International Obesity Task Force (IOTF) criteria.
Researchers found that by age seven more than half the children had a TV in their bedroom. By age eleven, 25% of the boys and 30% of girls were found to be overweight. The children who had TVs in their rooms had a significantly higher BMI and FMI than those who did not. This association was also stronger for girls than boys.
So should I take away my child’s TV?
It’s not quite as simple as that. Causality is often very difficult to prove. In this case, there were lots of variables, or differences, between the children. The researchers did adjust for these differences, which in scientific studies are known as “confounding variables“. They adjusted the results for child age, child BMI at nine months old and three years old, breastfeeding duration, child ethnicity, maternal BMI, maternal education, family income, bedtime at age seven and physical activity at age seven.
Despite these adjustments, it is still difficult to prove that bedroom screen media was the cause of the increased BMIs. We already know that levels of physical activity and an unhealthy diet are two of the biggest factors which contribute to obesity. It is likely that children who spend more time in front of screens have lower levels of physical activity. It is possible children who spent more time in front screens have poorer diets, possibly indulging in more junk food “TV dinners”. However, without a full in depth analysis of their diets and physical activity, it is impossible to prove that the increased obesity is directly caused by screen media.
The study doesn’t look at the children beyond the age of 11. It would be interesting to know what impact this increased BMI at a young age has in the longer term. Will these children grow up to be obese adults?
Current guidelines state that children should get at least sixty minutes of physical activity per day. So, ditching those bedroom TVs and encouraging your children to play outside isn’t such a bad idea anyway.
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Any opinions above are the author’s alone and may not represent those of his/her affiliations. Any comment is based on the best available evidence at the time of writing. All data is based on externally validated studies unless expressed otherwise. Novel data is representative of the sample surveyed. An online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice. Article edited for publication by Dr Hannah Arnstein
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Sources and Further Reading
- Longitudinal associations between television in the bedroom and body fatness in a UK cohort study available online at http://www.nature.com/ijo/journal/vaop/naam/abs/ijo2017129a.html