Jamie Oliver has warned children are coming to school with empty lunchboxes and no money for food as he called for more pupils to qualify for free meals.
The chef warned the most vulnerable in society were struggling from being excluded from the scheme.
It came as a joint campaign by The Independent and The Food Foundation urged the government to give meals to all schoolchildren living in poverty but who are not currently eligible.
Currently, households must earn under £7,400 a year - excluding benefits - to receive free school meals.
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Nearly two million children in England are eligible for the scheme. But charities warn 800,000 more are living in poverty and shut out from this vital support.
Oliver has called for more children to be covered by free school meals, saying the issue centred around “the most vulnerable kids”.
“We are talking about how bad is bad, the most vulnerable in society,” he told BBC Radio 4’s Today programme on Tuesday. “So you could be on benefits and still not get those free school meals.”
“If you earn over £7,400, you won’t get that free school lunch. But I think we’d all agree that there’s a massive gap between the means test for free school lunches as it stands and Universal Credit.
“I think what the government are saying is Universal Credit tethers off and can go up to sort of £30,000 - £40,000, but really we’re talking about the bulk of them being around £14,000 per household.
“What we have now is a situation where kids are coming in with nothing. They've got nothing on their card. They've got nothing in their lunch box.”
A joint investigation by The Independent and The Evening Standard revealed children were even stealing from shops and the school canteen as they struggled for food in the cost of living crisis.
Oliver said around 800,000 children should be getting free school meals who are not. “And the pressure on those parents are profound,” he said.
He said it was an issue of “fairness” if there were children “bouncing off the walls” because they had just had an energy drink for breakfast or asleep in class because they had not eaten at all.
“If you can create an environment where every child has the ability to thrive at school, we know in every way shape and form that kids who have a lunch and breakfast learn better,” Oliver told the Today programme.
“Their educational attainment is better. They do better, they get paid better, and they're more productive. But no one's taken it serious[ly] yet.”
Oliver said England was the “meanest” country in the UK when it came to free school meals.
Wales has given all primary school children free school meals from last month, while Scotland provides them to most primary school years. Northern Ireland includes families on Universal Credit with income up to £14,000.
Oliver said opening up the threshold for free school meals would also “inject funds into the system that would also really help to guarantee a much better service across 26,000 schools in the country”.
On Monday the school food industry warned it was “on its knees” as food prices soared. Charities said more free school meals - which are funded by the government - would help to support the sector.
