Children associate junk food with having a better time, while watching TV ads for unhealthy food makes them feel hungry, a new report has found.
Youngsters also love watching funny and engaging adverts and are able to recall advertising theme tunes, it said.
The study, for Cancer Research UK, was carried out in four primary schools in England and two in Scotland, among 137 children aged eight to 12.
Small groups were shown two adverts for foods high in fat, sugar or salt and discussions were held about them and about eating in general.
The results suggest that, despite current rules saying junk food cannot be promoted during children's TV shows, youngsters are heavily influenced by the adverts at other times of day.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Pupils watched family programmes between around 7pm and 8pm each day and also on weekends, which researchers said exposes "the loophole in the current legislation".
TV advertising also results in children pestering their parents that can lead to the purchase of junk food, the report said.
Researchers found the children had a good level of nutritional knowledge but ads tempted them into eating unhealthy foods.
They also reported children saying the adverts made them hungry and wanting to eat junk food.
In the longer term, children remembered the adverts, bright colours and packaging, leading to the possibility they would ask for specific products in supermarkets.
Cancer Research UK is among several charities calling for a ban on junk food advertising on TV before the 9pm watershed.
