Watch: Jamie Oliver's Fight for Fit Foods

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ET caught up with Jamie Oliver backstage at the Late Show with David Letterman to talk about his ongoing fight for healthy foods as his show "Jamie Oliver's Food Revolution" gets set to premiere its second season. However this time around, Jamie takes on his biggest challenge yet: the Los Angeles Unified School District.

The process wasn't easy as the charismatic celebrity chef asserts he was banned from every single school "before he landed in the plane." He's even had to resort to guerilla tactics and other stunts to get things moving.

"The only way I could get into the schools was if I became a teacher," Jamie proclaims. "I was teaching food but in math, in science, in social studies, you name it."

This year proved to be tough for Jamie, having to battle the school board in which he equated to as a "nightmare." The health campaigner persevered on his journey to accomplish his show's true purpose: to make a change. "When you start to stir the pot, everyone starts making a little bit of change."

When the conversation moved to the royal wedding and what he'd cook for it, Jamie seemed to lighten up as well with a few jokes. "I'm sure they're going to go home and have a proper wedding, like 30 people and a bit of a laugh," he quips. The colorful cook then makes claims on Britain's dominance in the wedding department, finds Prince William and Kate Middleton to be a solid match and holds royal events like these in high prestige which always seem to leave the British chef in awe.

Find out what else Jamie said in the video and be sure to check out the season premiere of "Jamie Oliver's Food Revolution" Tuesday April 12 on ABC!