There is no point improving school food if pupils go to take-aways, says minister
Pupils should be kept in school grounds during lunch breaks to stop them eating unhealthy take-away food, the Schools Secretary Ed Balls has said.
Mr Balls says there is little point in banning junk food inside school, if pupils then eat it outside school.
This will not be a compulsory requirement, but Mr Balls says he will back heads trying to impose a policy of not allowing pupils out during the day.
He also wants councils to limit the number of take-aways near schools.
Mr Balls is set to address the Healthy Eating in Schools Conference in London - where he will claim that "the corner has been turned" on improving the quality of school meals.
Since the Jamie Oliver-inspired campaign to improve school food, there has been a series of initiatives, costing £650m, designed to raise the nutritional content and appeal of school meals.
Ed Balls wants healthy eating to extend beyond the school gates
But Mr Balls will tell the conference that attention needs to be paid to what children are eating outside school.
"There is no point in banning junk food and raising the quality of lunches in schools, if teenagers can simply go to eat unhealthy food from neighbouring take-aways," says Mr Balls.
As such, he says he supports "stay-on site" policies, in which pupils are not allowed to leave school premises during the day - stopping them from eating in local fast-food shops.
This will help to tackle an "ingrained culture of unhealthy eating", he says.
Mr Balls also backs local authority efforts to limit access to fast food - such as imposing a ban on take-aways within 400 metres of secondary school gates.
A survey of secondary school pupil eating habits published this summer found that 80% of pupils bought food from local shops.
The research by the Nutrition Policy Unit of London Metropolitan University found that two in five pupils never used the school canteen.
An important factor in eating habits was the speed and convenience of getting food from local take-aways, rather than queuing and overcrowding in school canteens, found researchers.
Rather than the quality or cost of school food being the determining factors, it was often the lack of comfort in the school canteen that influenced pupils.
The study found that local shops were more entrepreneurial about meeting this demand - offering cut-price child-size portions and getting in extra staff so that children could be served quickly.
However, this meant that children were ignoring healthy food in school and buying food and drink with high levels of fat and sugar.
A survey from the NHS Information Centre earlier this year found that one in three 11-year-olds is overweight or obese.