The study, published in The Journal of Pediatrics, finds that celebrity endorsement of a food product encourages children to eat more of the endorsed product, especially when the celebrity is seen in a different context through the advert.
"This is the first study to show the powerful effects of celebrity endorsement - in both a TV advertising and a non-food context - on the choice and intake of the endorsed snack product over the same product offered as a non-branded snack item," said Dr Emma Boyland, from the University of Liverpool.
"The study demonstrated, for the first time, that the influence of the celebrity extended even further than expected and prompted the children to eat the endorsed product even when they saw the celebrity outside of any actual promotion for the brand," said Boyland, who led the research study. "It quantifies the significant influence that the celebrity has over children's brand preferences and actual consumption."
The research team conclude that their work has 'important consequences' for celebrity's - and especially sports stars - who promote the consumption of unhealthy or high fat, salt and sugar (HFSS) products via endorsements:
"If celebrity endorsement of HFSS products continues and their appearance in other contexts prompts unhealthy food intake then this would mean that the more prominent the celebrity the more detrimental the effects on children's diets," said Boyland.
The study involved 181 children, aged between 8 and 11 years old, who were asked to watch one of three different adverts or general TV footage. The team used former England international football player Gary Lineker's endorsement of Walker's Crisps in the UK as an example of celebrity endorsement.
The former football (soccer) player is now principally a TV sports presenter in the UK, and has been endorsing Walker's Crisps there since 1995.
The children were shown a sample of TV, including cartoons and a sports show that Lineker presents. Alongside these programmes, the group were shown one of three adverts - one for a toy, or for one of two for snack foods - one of which was Walker's Crisps.
The children were offered two bowls of crisps to eat, one labelled `Walkers' and one labelled `Supermarket' - although both bowls actually contained Walkers crisps.
The amount of crisps consumed from each bowl by each child was then measured.
Boyland and her team reported that although both bowls contained Walkers crisps, after watching the Gary Lineker advert or the general TV footage of Gary Lineker, the children ate considerably more of the Walkers crisps than the children who watched the other snack food advert or the toy advert.