More evidence links screen time with childhood obesity

04-Mar-2021 - Last updated on 04-Mar-2021 at 15:48 GMT

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With the food industry under increased pressure to promote healthier diets, address obesity and reduce diet-related diseases, more evidence emerges to suggest environmental factors, specifically screen time and poor sleep, may go hand-in-hand with overconsumption.

Children who have more screen time at ages 9-10 are more likely to develop a binge-eating disorder one year later, according to a study.

Researchers in the US analysed data over three years from 11,025 children 9-11-years old. The children answered questions about their time spent on six different screen time modalities, including television, social media, and texting. Parents answered questions about their children's binge-eating behaviours, specifically the frequency and characteristics of overeating and related distress.

The study, published in the International Journal of Eating Disorders this week, found that each additional hour spent on social media was associated with a 62% higher risk of binge-eating disorder one year later. It also found that each additional hour spent watching or streaming television or movies led to a 39% higher risk of binge-eating disorder one year later.

"Children may be more prone to overeating while distracted in front of screens. They may also be exposed to more food advertisements on television. Binge-watching television may lead to binge-eating behaviours because of overconsumption and a loss of control," said lead author, Jason Nagata, assistant professor of paediatrics at the University of California, San Francisco.

"Exposure to social media and unattainable body ideals may lead to a negative body image and subsequent binge eating," added senior author, Kyle T. Ganson, assistant professor at the University of Toronto's Factor-Inwentash Faculty of Social Work. "This study emphasizes the need for more research on how screen time impacts the well-being of young people now and in the future."

While the study was conducted prior to COVID-19, its findings are especially relevant during the pandemic. "With remote learning, the cancellation of youth sports, and social isolation, children are currently exposed to unprecedented levels of screen time," said Nagata.

Increased screen time associated with childhood obesity risk

Previous studies indicate that both screen time and sleep duration are associated with becoming overweight.

Over a five-year period, researchers from the Royal College of Surgeons in Ireland examined associations between screen time, sleep duration, and overweightness in 4,285 children (aged 2 to 11 years old) in eight countries (Spain, Germany, Hungary, Italy, Cyprus, Estonia, Sweden, and Belgium).

Parents were asked to report how much time children spent on average watching TV, playing games consoles, using a mobile, computer or tablet, and sleeping each day at the start of the study.

Analyses of 3,734 children who were not overweight or obese at the start of the study, found that for every extra hour of screen viewing children were 16% more likely to become overweight or obese during follow-up, whilst every hour less of sleep was associated with a 23% increased risk of overweight or obesity.

Although an observational study, meaning no conclusions about cause and effect can be drawn, the researchers said these new findings corroborate evidence from previous studies that indicate that both sleep duration and screen time are independently associated with becoming overweight.

They urged screen time and sleep duration to be considered as part of any prevention strategies to reduce the burden of overweight and obesity and related health conditions.

Global trends suggest that children's sleep time is decreasing, whilst screen time and overweight and obesity are increasing, they noted. It has been reported that worldwide, 90% of adolescents are not sleeping the recommended nine to 11 hours per night, which has coincided with an increase in the use of screen-based devices. In the UK, it is estimated that young people (aged 8 to 19 years old) spend an estimated 44 hours a week on average looking at screens.

The study’s authors said a deeper understanding of the modifiable risk factors leading to excess weight in children and adolescents could provide unique opportunities for preventing the immediate and long-lasting health consequences of becoming overweight.

"Our study highlights the potential of overweight and obesity prevention strategies that promote adequate sleep duration and limit screen time, given that both independently predicted incident overweight in our study,” said Dr Viveka Guzman from the Royal College of Surgeons in Ireland who led the research.

"Sleep is an often undervalued but important part of children's development, with a regular lack of sleep causing a variety of health problems. Our findings suggest that sleep duration plays a role in the link between screen time and overweight, but more research is need to understand the mechanism underlying this relationship."

Other research from the British Nutrition Foundation has warned that adults and children are not getting enough sleep, putting them at risk of poor diets and obesity.

Its study last year revealed over 40% of UK adults slept less than the recommended seven hours, while 32% of primary school children and 70% of secondary school children failed to sleep the suggested nine hours. The survey also hinted that using screens before bed was a factor in poor sleep.

Bridget Benelam, Nutrition Communications Manager at the BNF, told FoodNavigator. “We don’t know exactly why a lack of, or poor-quality sleep influences our food choices, but it may due to changes in appetite, being awake for longer and also that we may feel less like being active.”