The study by researchers in the Institute of Psychology, Health and Society examined the food preferences of a group of 281 children aged six to 13 years old from the North West of England.
The children were shown an episode of a popular cartoon before being shown it again two weeks later. In each case, the cartoon was preceded by five minutes of commercials – one set showing toy adverts and one showing mainly snacks and fast food. After each showing the children were given lists of various food items, both branded and unbranded, and asked what they would like to eat.
The study found that after viewing the food commercials the children were more likely to pick unhealthy foods. All the children chose more branded and non-branded fat-rich and carbohydrate-rich items from the food preference lists compared with those they chose after viewing the toy adverts.
Why watching TV is making kids fat
The study also found that children who watched television for more than 21 hours a week were more likely to be affected by the food adverts than those children who watched a lesser amount of television. These children also had a significantly greater body mass index than those who were less frequent viewers.
Emma Boyland, from the University's Kissileff Laboratory for the Study of Human Ingestive Behaviour, said: "Obesity in young children is now a major health concern around the world. Our studies highlight that there are global connections between advertising, food preferences and consumption. This is a beyond-brand effect, increasing children's selections of all unhealthy foods – not just those shown in adverts.
"This study demonstrates that children are far more likely to eat unhealthy foods if they watch a lot of television. This suggests that it would be beneficial to reduce the amount of television that children watch. These findings also have implications for the regulation of television food advertising to children.
A 9pm watershed should be introduced so that children are not exposed to high fat, high sugar and high salt food advertising during popular family viewing."