A head teacher is leading a review into whether there has been a decline in the quality of school dinners during Covid.
Head teacher Dr Nick Capstick, of Drove Primary School, in Wiltshire, said the government needed to show "real leadership" over school meals.
Rising costs, staffing shortages and shorter school lunch breaks are some of the challenges providers say they face.
The Department for Education said it was up to schools to enter contracts that delivered healthy hot meals.
Dr Capstick said getting children into great habits at school would create "a really healthy and sustainable future for our kids".
He is leading the School Food Review in his capacity as chief executive of the White Horse Federation, a trust of 32 primary schools, secondary schools, and special schools that focuses on "areas of high disadvantage" in south west England.
He says the pandemic has been "incredibly difficult" for pupils, parents, teachers and frontline teams that support schools.
'Grab and go'
But as schools started to look beyond Covid, Dr Capstick said the review's working group was "building the case for a post-Covid reset of school food".
The review has been organised by the Bite Back 2030 charity, which aims for all children to have access to healthy and nutritious food.
James Toop, chief executive of the charity, said healthy food had been replaced with a "grab and go culture [which] has emerged in many schools… and typically those things are deep fried".
"Many young people don't want to sit down and eat food," he added, and even the "grab and go" food picked out of the freezer and reheated was "much more likely to be processed and less healthy as well."
Caterer Kymee Cleasby, of Sue Brady Catering, in Marlborough, which supplies meals for primary schools and nurseries, said: "It's incredibly difficult... the cost of food is soaring through all of our suppliers, through no fault of theirs.
"It's partly through Covid, partly through Brexit, all sorts of things have come together to create the perfect storm."
The caterer added the pressure on the industry meant some "won't be able to resist" cutting costs and some caterers would close rather than go back to supplying "turkey twizzlers".
She added the people prepared to supply unhealthier food would be the ones left in the industry "and we don't want that for our children surely".
In 2005, TV chef and personality Jamie Oliver heavily criticized 'turkey twizzler' school meals in a Channel 4 programme.
He said although he might feed a "turkey twizzler' school meal to his dog he "wouldn't feed it to my mate, certainly not my kids".
He led a a Feed Me Better petition, which resulted in an extra £280m of government funding over three years being spent on improving English school meals.
The Bite Back charity, which Mr Oliver backs, has found many caterers appear to be bolstering their income by offering unhealthy treats and fizzy drinks for extra charge.
The Department for Education said funding to pay for school meals would rise by 2% per pupil in the next financial year.