The British Dietetic Association has accused the Youth Sport Trust of glamourising fatty foods by linking with a confectioner for a child health awareness appeal.
Cadbury is set to sponsor the Youth Sport Trust in a £8 million programme that works with schools to promote sports and health, and encourages children to get more exercise.
Wendy Doyle, national spokesperson for the association, said: "Even though it's obviously a lot of money, it's difficult to justify linking a sports trust with a company that makes unhealthy food."
Doyle said that obesity levels in children were rising, and that any campaign promoted by a company that manufactures fat-filled food products would send out a potentially dangerous message.
"Often these companies receive a lot of criticism for producing unhealthy foods and the best way to get to people is by supporting good causes," she said.
The trust was unavailable for comment.