A new healthy eating policy introduced in Northern Ireland's schools last month has resulted in pupils deserting canteens for the local chip shop.
Chef Jamie Oliver campaigned for healthier school meals
A BBC survey of all five education boards found school cafeteria incomes had fallen in three boards with an average drop of more than 7%.
One school in Craigavon has suffered a 30% decrease in takings.
The new policy forced canteens to cut back on fatty foods like chips and stop selling fizzy drinks packed with sugar.
At the same time, canteen prices have risen while pupil numbers have dropped.
Schools report that where pupils are allowed out at lunchtime, they are going to local shops to buy unhealthy food.
Those who are not allowed to leave the school gates are bringing more packed lunches.
At the same time, canteens are throwing out more wasted food and there are fears that the loss in business could cost jobs among catering staff.
However, schools say they are hopeful things will improve once pupils get used to the changes.