An Ofsted report this week said that improvements to menus, made after a campaign by celebrity chef Jamie Oliver, had led to a significant reduction in the number of pupils opting to eat school food. Demand had dropped by up to a quarter in 19 of the 27 schools in the study after healthier meals were introduced.
One secondary school pupil "quipped that he had become far fitter as a result of regular walks to the nearby chip shop".
Changes to lunches, which have replaced chips and fried food with salads and vegetables, were not properly marketed to children or parents, the report said.
Prices are also responsible for their decline in popularity, with both parents and headteachers saying meals had become prohibitively expensive for some children.
"If this trend continues, the impact of the Government's food policies will have limited effect," inspectors warned. "This will be particularly the case for children from more vulnerable families."
Payment methods that identify children receiving free school meals were exacerbating the situation.
John Dunford, general secretary of the Association of School and College Leaders, said: "It is not surprising that if a school goes suddenly from traditionally unhealthy menus to Jamie Oliver-inspired menus, the number of pupils will go down, unless the school has done some serious marketing."
New regulations governing the standards of school food were introduced in September 2006, which banned chocolate and sweet fizzy drinks. From last month the rules were extended to include all food for sale as well as lunches.
Despite all the schools in the report meeting the minimum requirements, some still did not have kitchens on site. Those schools had to rely on microwaves to reheat food made elsewhere, and in some cases children were served cold meals.
None of the secondary schools visited provided good quality dining arrangements and were often overcrowded and noisy.
However, some schools have bucked the trend. As the TES reported last year, Southfield School for Girls in Kettering, Northamptonshire, has improved its meal takings from pound;100 to pound;800 a day by bringing in a resident professional chef who produces a menu embracing lamb kebab, loin of cod with parsnip crumble and stonebaked pizzas.
* 'Food in schools: encouraging healthier eating' is at: www.ofsted.gov.uk