Children who miss out on nutritious meals because they are at the back of the dinner queue were not included in figures released to show the state of school lunches.
As reported in last week's TES, Ruth Kelly, Education Secretary, has announced a drive to make school lunches healthier.
Jamie Oliver, the celebrity chef, met Mrs Kelly in Downing Street a week before her statement to argue the case for higher-quality school food.
To soften the announcement, the Government claimed that 83 per cent of secondaries were already meeting current nutritional standards every lunchtime.
But the figure, taken from a Department for Education and Skills report, only applied to children who arrived first for lunch. Just 47 per cent of schools met the targets for pupils at the end of the queue because the healthy options have run out. The Conservatives described the figures as a "shabby misuse of statistics to prove a point".
Peter Melchett, policy director of the Soil Association, said: "There is a reluctance to admit the scale of the problem, especially as the current DfES standards are not what normal people would think of as nutritional."
Ms Kelly announced cuts in salt, sugar and fat in processed foods, and the establishment of an independent school food trust, and called for parents to help.
The details of the new nutritional standards for lunches, which will be enforced from September, are expected to be sent to schools in April.
Headteachers supported the moves in principle but said that getting healthy food on the menu was only half the battle; children then had to be persuaded to eat it.
Keith Scott, assistant head of Appleby grammar school, Cumbria, said around 90 percent of his 540 pupils ate school dinners. "Because we are a relatively remote, rural community, we try and source our fresh produce as locally as possible - like beef from local farms for our roast dinners - and do a lot of cooking and baking from fresh ingredients," he said.
"But there are still those who will go and get a double plate of chips and gravy. We teach about a healthy lifestyle in food technology and citizenship - we have to hope that will change habits."
Jamie Oliver spent two weeks trying to improve the lunches at Kidbrooke school in Greenwich as part of a new Channel 4 series, which begins on Wednesday.
Mr Oliver said that Ms Kelly's plans would fail without increased funding.
He warned that if the Government did not decide to ban junk food from schools entirely it would show that "they don't give a shit about kids" friday magazine cover story Jamie's School Dinners begins on February 23, 9pm on Channel 4