A Welsh Labour MP has launched an attempt to ban junk food from school vending machines.
Vending machines in schools often sell high-fat products
Jon Owen Jones, the MP for Cardiff Central, said a ban would help reduce the problem of obesity.
Mr Jones said: "At the age of six, one in five children are overweight, and one in 10 are obese. By the age of 15 this has risen to 31% and 17%."
He introduced a bill in the House of Commons on Tuesday that would prevent schools selling high fat food and drinks to their pupils.
Mr Jones said he was trying to change the law as part of a drive to cut obesity - adding that it was one step towards tackling Britain's weight problem.
As a member of the Health Select Committee he has been part of an investigation into obesity.
"This problem has doubled since 1982 and seems to be getting worse," he claimed.
"Banning junk food from vending machines will not solve this problem but it is an important first step.
"We should not undo in the corridor all the work done in the classroom on healthy eating."
Jon Owen Jones is a member of the Health Select Committee
Several USA States and schools district have already taken this step, and the Labour MP said the UK should not wait until it had America's levels of obesity before it took action.
"I hope the government will listen to my arguments and legislate on this issue themselves."
A spokesman from the British Heart Foundation said that the nutritional content of vending machines in schools was a problem.
"Obese and over-weight children tend to become obese and over-weight adults leading to a range of health problems.
"Obese children also run the risk of developing type II diabetes," he added.
Mr Jones' bill cannot become law without government support, but he said that he hopes it will help raise the profile of his campaign on the issue.
At Willows Comprehensive School in Cardiff, part of the students' personal and social education (PSE) programme looks at healthy eating.
Teacher Ian Whittaker said: "What we look at is how to promote healthy eating through our curriculum within the classroom but also through the choices we offer kids in school."
He thinks vending machines can undermine the work being done with pupils.
"I feel we are trying our hardest to promote values in our children and yet at the same time the vending machines are actually promoting unhealthy eating," he added.
One pupil said: "In the vending machine, there is mostly crisps, chocolate and fizzy drinks.
"If it was all healthy then more pupils would go for it, but not everybody, so quite a lot would go to waste."