Cancer Research UK warned that being bombarded by TV adverts for unhealthy, high-calorie food could lead youngsters to eat more than 500 extra snacks such as crisps, biscuits and fizzy drinks throughout the course of a single year.
When they watched TV without adverts, researchers found no link between screen time and the likelihood of eating more junk food, suggesting that the adverts on commercial TV may be driving youngsters to snack on more unhealthy food.
Regularly eating high-calorie food and drink – which usually have higher levels of fat and sugar – increases the risk of becoming overweight or obese.
More than one in three British teenagers are overweight or obese, with obesity the second biggest preventable cause of cancer in the UK after smoking, and linked to 13 types of cancer including bowel, breast and pancreatic.
Lead author Dr Jyotsna Vohra said: “This is the strongest evidence yet that junk food adverts could increase how much teens choose to eat.
“We’re not claiming that every teenager who watches commercial TV will gorge on junk food, but this research suggests there is a strong association between advertisements and eating habits.
“It’s been 10 years since the first, and only, TV junk food marketing regulations were introduced by Ofcom and they’re seriously out of date.
“Ofcom must stop junk food adverts being shown during programmes that are popular with young people, such as talent shows and football matches, where there’s currently no regulation.
“Our report suggests that reducing junk food TV marketing could help to halt the obesity crisis.”
The Obesity Health Alliance (OHA) recently called for a 9pm watershed to protect children from junk food marketing after observing that more than half of food and drinks adverts shown during popular family TV shows were for products high in fat, sugar and salt, which would be banned from children’s TV channels.
In one case, researchers observed nine junk food adverts in just 30 minutes.
Professor Linda Bauld, Cancer Research UK’s prevention expert, said: “Obese children are five times more likely to remain obese as adults, which can increase their risk of cancer later in life.
“The food industry will continue to push their products into the minds of teens if they’re allowed to do so. The Government needs to work with Ofcom to protect the health of the next generation.”
The charity based the study on a YouGov survey, which questioned 3,348 young people in the UK between the ages of 11 and 19 on their TV viewing habits and diet.