Young children who spent more than half an hour a day online were almost twice as likely to pester their parents for junk food, according to a Cancer Research UK report.
And primary school children who spent more than three hours on the web were more than four times more likely to spend their pocket money on chocolate, crisps, sugary drinks and takeaways than their peers who browsed for less than half an hour.
These children were also 79% more likely to be overweight or obese while those who were online between 30 minutes and three hours a day were 53% more likely to be carrying excess weight than those who were online for less.
Obese children are five times more likely to remain obese into adulthood and being overweight or obese as an adult increases the risk of 13 different types of cancer.
Teams from the University of Liverpool and Cancer Research UK’s Cancer Policy Research Centre asked almost 2,500 seven to 11-year-olds and their parents about their eating habits and how much screen time they had, outside of doing homework.
Researchers found that, on average, children were online for 16 hours a week – not including time spent for homework – and watched 22 hours of television per week.
The amount of exercise done by the children had no impact on the results, showing that for this research, excess weight wasn’t linked with being sedentary.
Each additional hour of commercial TV that children watched was linked with an increased likelihood of pestering their parents to buy products they’d seen advertised.
They were four times more likely to buy chocolate and over three times more likely to buy sugary drinks if they watched more than three hours of commercial TV everyday compared to youngsters who didn’t watch as much and 59% more likely to be obese or overweight.
Dr Emma Boyland, a lead researcher from the University of Liverpool, said: “Young children who spend more time on the Internet and watching commercial TV are more likely to pester for, buy and eat unhealthy food and drinks.
“Parents are all too familiar with being nagged for sweets and fizzy drinks in the supermarket or corner shop. Our research shows that this behaviour can be linked to the amount of time children spend in front of a screen and as a result, the increased number of enticing adverts they see for these sorts of products.”
The UK government has published plans to halve childhood obesity by 2030 and will be opening consultations on policies including a 9pm watershed for unhealthy food adverts on TV, and how best to regulate on-demand and online adverts.
Dr Jyotsna Vohra, head of the Cancer Policy Research Centre at Cancer Research UK, said: “Obesity is the biggest preventable cause of cancer in the UK after smoking so it’s vital we see a 9pm watershed on junk food adverts on TV and similar protection for children viewing adverts on-demand and online.
“The evidence suggests that time spent online, where advertising can be prolific, and watching commercial TV increases the likelihood that children will pester for, buy and eat more unhealthy foods. If they didn’t then the food industry wouldn’t spend so much on advertising.”