Contract caterers have warned that jobs may be lost unless the current dip in school meals uptake is reversed.
"We need to drive sales back up and if that doesn't work we will need to start making cuts," said Stephen Thorns, Sodexho's director for commercial education.
Following Jamie Oliver's TV programme, there has been a fall in take-up of between 8% and 15% across Sodexho's school meal contracts.
Initial said it has seen an average 6% fall. A spokeswoman said: "Although we haven't cut hours or jobs yet we are currently looking closely at staffing levels for September."
Others contractors claim not to have been affected. A spokeswoman for Harrison Catering said: "We have been very careful to communicate with parents both before and after Jamie Oliver [TV series] to make sure we're not all tarred with the same brush."
A Scolarest spokeswoman put the fall down a seasonal trend for lower school meal uptake in the summer.