Moves to improve the quality of meals in English secondary schools have resulted in fewer pupils taking them this term, a BBC News survey suggests.
The government is striving to improve the quality of school meals
Fifty-nine local authorities responded, of which 35 (59%) said the number of pupils eating dinners had gone down.
Of those, 71% agreed Jamie Oliver's healthy meals campaign was a reason.
However, the School Food Trust - set up by the government in 2005 to improve school food - predicted that the downturn would be temporary.
Chief executive Judy Hargadon said: "We expected there to be a bit of a downturn; children are going to have to get used to eating more healthy food at school and it takes a while for them to get used to that.
"Some schools have however proved that it can be done and that children really enjoy eating healthy food, so our job is to help people get through this dip."
Of the 59 authorities that responded to the survey, six had more pupils taking meals, eight reported no change and 10 said the changes were not applicable.
Half said a factor in the decline was the restrictions imposed on vending machines, while some said the prolonged warm weather had had an effect.
Overall the decline was just 5.8%, though individual areas had seen decreases of as much as 30%.
Declining pupil take-up of school meals has also been reported in Scotland and Wales, following drives there to improve the quality.
Children's Minister Parmjit Dhanda said the government was committed to the change.
SHORT LUNCH BREAKS
The only child getting 25 minutes to eat is the first one in the queue
Local Authority Caterers Association
"I'm not saying that there aren't issues, because there are. But it's still early days," he said.
"We're investing for the long term here. We're putting in money, something like £477m right up to the year 2011 and that's pretty unprecedented.
"There hasn't been a subsidy for school meals since the 1960s and we're focused on this because we think it's the right thing to do."
Irene Carroll, national chairman of the Local Authority Caterers Association, said a key problem was that children were not being given healthy food by their parents.
"Jamie hung his programme on school meals. It was a shame because school meals weren't the real problem," she said.
Jamie Oliver has run a high-profile campaign to improve nutrition
"It's what they are eating out of school that is the problem. We have got to really work hard educating the children on why they should be eating this."
Mrs Carroll added that another issue affecting school dinner take up was shorter lunch breaks which give pupils no time to eat full meals.
"Lunch time periods now are so short," she said.
"Ideally we would look to give them a plated meal and pudding. But they have got 30 minutes and in many cases they've got 25 minutes.
"And the only child getting 25 minutes to eat is the first one in the queue."