Jamie Oliver has compared unhealthy packed lunches with child abuse and said the Government should do more to improve school meals.
The celebrity chef was supported by TV presenter Kirstie Allsopp and Olympian Victoria Pendleton outside Jamie's Fifteen restaurant in Shoreditch, London, to raise awareness about home cooking and healthy food.
Oliver criticised parents for giving children unhealthy packed lunches, saying: "I'd say some are close to child abuse so I think we're all talking about school dinners here, yes let's, let's do it and let's do it properly.
"Coming through the door every day are 60, 70 per cent packed lunches and they're not monitored and we've no right to monitor them.
"So it's really down to the head teacher and their confidence to be able to do what they can."
Oliver said he disagreed with Education Secretary Michael Gove about nutritional standards in secondary schools and added: "There's still a lot to be done and I guess from the big picture you want the most hardest to reach kids, the most at risk to be looked after efficiently."
Oliver, who was speaking at a street party for his Food Revolution Day, said he was also working with businesses to combat unhealthy food at work.
He said: "What are you feeding your staff, is it all bad choices? What's in the vending machine, is it all bad choices? Probably. Possibly."
The chef also said he had been working on a new season of his TV show Food Fight Club, which will be aired at the end of this year, and another project about cooking on a tight budget.
Kirstie Allsopp added that introducing children to healthy food was difficult but worthwhile.
She said: "The first time I showed lentils to the children they just looked at me like I was insane."
Kirstie said children's food was not a "mum issue" but a family issue, adding: "I know a great many men who cook really well, most of our top chefs are men, why doesn't that translate into the home?"
The TV presenter said she was working on a new show called Fill Your House for Free about freecycling instead of throwing items away.
Speaking at the event, Olympic cyclist Victoria Pendleton said the news Sir Bradley Wiggins was withdrawing from the Giro d'Italia was "devastating".
She said: "It's one of the things that as an athlete you fear most is getting ill or getting injury because you've no control over it.
"And you put so much work and preparation into a competition on one single day or you know one week or two weeks of your life and it's devastating when you can't do anything about it.
"I've had injuries before that have stopped me from training and when your job is to train it's the most frustrating thing in the world.
"As an athlete you always want to do more so it's hard to be told to stop or to hold back. It takes the people around you really a lot of the time to convince you to back off, to stop and quit."
The Olympic champion said she was now taking time to plan her wedding to her fiance Scott Gardner, which will be held in September.
Jamie's Food Revolution Day was celebrated with events in 75 countries.
The Shoreditch street party included food stalls, live music and workshops, and Oliver said other events were held as far afield as Chile, New Zealand and Sierra Leone.