Junk food advertising should be banned in an effort to reduce childhood obesity, the Liberal Democrat education spokesman has said.
Many children prefer junk food, Mr Davey said.
Ed Davey said it was important to create a "cultural shift" away from fizzy drinks, fat and salt towards better nutrition.
Behaviour and long-term health were suffering, he told a fringe meeting at the Lib Dem conference in Blackpool.
Mr Davey also called for increased budgets for school dinners.
The government is providing £220m for schools and local authorities in England so that they can spend at least 50p on ingredients per pupil per day for primary schools, and 60p in secondary schools
Mr Davey said: "Should we be banning the advertising of junk food? I think we should.
"It's about changing behaviour and the tastes of children, because of advertising and the sort of food children are used to.
"Often when healthy food is brought into school, children don't like it.
"It isn't just about money and training for school staff; it's about a more cultural shift, involving education for the children and the parents."
Ministers have put aside £60m for a School Food Trust to advise schools - and parents - on healthier meals.
A panel of experts will draw up guidelines for caterers to follow, starting from this autumn. They will become mandatory from September 2006.