Jamie Oliver has criticised Education Secretary Michael Gove for "eroding" healthy school meal standards.
The TV chef raised concerns that academy schools are not obliged to sign up to food standards introduced by the previous government.
He called on parents to tell Mr Gove not to touch the rules, warning that a move away from them would be a disaster.
Oliver told BBC News: "The bit of work that we did which is law was a good bit of work for any government. So to erode it, which is essentially what Mr Gove is doing - his view is we let schools do what they want.
"I think that's a wonderful ambition, that everyone's going to be brilliant, but headteachers are more pushed than ever, expected to do more than ever, now they have to be entrepreneurial caterers as well as everything else they have to do.
"The standards are there to really keep everyone on their game. It's not a large amount of paperwork, it really isn't, and for what it's for, which is essentially the future of our country, it's really important."
More than two-fifths of primary school children and a third of secondary school pupils are now opting for school meals, according to the latest official figures.
Take-up has been growing since the school meals revolution was kick-started by Oliver six years ago when he began a campaign for better quality school dinners.
It won widespread public support and led to strict nutritional guidelines for meals introduced to primary schools in 2008 and secondaries in 2009.
But academies, which are semi-independent state schools, do not have to sign up, and since last year, the coalition Government has allowed any school to apply for academy status.