"Put a man on the moon 40 years ago, don't tell me that we can't make healthy, delicious, tasty, attractive food for teenagers in the province of Ontario in 2012," he said.
Some cafeterias aren't making enough money because they have to cut out food that doesn't adhere to the provincial guidelines. The Toronto District School Board said it's looking at closing some cafeterias that are making as little as $35 a week.
But McGuinty was unsympathetic, saying he has to ensure that students have access to healthier fare — even if that means that some cafeterias go out of business.
"I guess we'll have to get a bit more creative in terms of what it is we're selling there and making available to students there," he said.
But some students want their junk food back.
Two students in Brampton, Ont., are fighting to bring pizza, coffee, chips and chocolate bars back in their cafeteria, even making a YouTube video protest the junk food ban.
The video, made by Samuel Battista and Brian Baah of St. Thomas Aquinas High School, interviews students who say they're no longer going to the cafeteria and are buying their food elsewhere.
Battista takes a tour of the cafeteria to show the limited options available to students, such as diet soda, baked fries and whole grain cupcakes.
Schools are losing money, which means there's less money to support students, he says.
"How can the government expect students to make the right choices if the government themselves are taking away these choices?" Battista says in the video.
The Progressive Conservatives dismissed the healthy food guidelines as yet another example of a Liberal government that wants to dictate every aspect of people's lives.
Cafeterias should provide nutritional foods, but students should also have a choice in what they eat, said Tory critic Rob Milligan.
His alma mater, Campbellford District High School in Trent Hills, Ont., also saw revenue drop, which means less money for sports teams and other extracurricular activities, he said.
"It's not up to government to dictate as to what people's personal choices are," Milligan said.
"These students are well-educated and can make decisions for themselves."
There are concerns that the government isn't monitoring the new policy closely enough to see what kind of effect it's having on students and schools.
Education Minister Laurel Broten said last week that she hadn't heard any complaints about cafeterias losing money. But she changed her tune Tuesday, acknowledging that some of them may have to close.
"I will be looking into this issue to understand what is transpiring across the province, because I do not accept that it is an impossible task that we have asked boards to do," she said.
The government shouldn't back down on making sure there are healthy options in school cafeterias, but they should be keeping better tabs on the policies they implement, said NDP Leader Andrea Horwath.
"I do believe that the schools should redouble their efforts and make sure those cafeterias do everything they can to try to turn this around before abandoning it," she said.
"Because really, in the long run, it's the right thing to do."
The Healthy Food for Healthy Schools Act, which took effect last fall, requires all publicly funded schools to meet mandatory nutrition standards for food and drinks sold in schools, including vending machines.
It bans items like candy, energy drinks and fried foods from being sold in schools and requires that 80 per cent of school menus must include products with the highest levels of essential nutrients and the lowest amounts of fat, sugar and sodium, such as fruit, vegetables and whole grain breads.