Head teachers in England are being urged to ban packed lunches to ensure children eat healthy school dinners, the BBC has reported.
The advice is part of government-commissioned school food review led by the two founders of the Leon restaurant chain and is due to be published today by the Department of Health.
The School Food Plan was set up amid concerns that many youngsters are still being served unhealthy meals, and more needs to be done to boost food standards in all schools.
Henry Dimbleby and John Vincent have spent more than a year working with schools, councils, caterers, parents and the government to put together the review.
It says take-up of school dinners is low at 43% despite huge quality improvements, and that only 1% of packed lunches meet the nutritional standards of school food, the BBC said.
Heads are being encouraged to make the price of lunches more affordable.
Sharon Hodgson MP, Labour's Shadow Children's Minister said: "All the evidence shows that a filling and nutritious school lunch can improve attainment and health, and when the country is in the middle of a childhood obesity crisis, it is important that schools are doing their part to improve diets.
"Labour vastly improved the quality of school food after Jamie Oliver's important campaign. David Cameron and Michael Gove have deliberately undermined that progress by exempting academies and free schools from Labour's rules, and junk food has crept back into canteens and vending machines.
"Parents deserve to have confidence in the quality of school meals. Labour's food standards should apply in all schools, and Michael Gove needs to perform another U-turn to ensure they do."