Ronald McDonald, the world's most recognizable fast-food mascot, is the newest fitness expert in Fredericton elementary schools.

The red-haired clown is most often connected with selling hamburgers, French fries and milkshakes for the fast-food giant, McDonald's Restaurants.

But his job description appears to have changed. During the last several months, the clown has jogged his big red sneakers into several Fredericton elementary schools to preach the gospel of healthy living.

That McDonald's has found a way to get its marketing tool in front of school children worries nutrition expert Marion Nestle.

The New York University professor is considered one of North America's leading experts on nutrition and the fast-food industry, and says McDonald's is thinking about more than promoting fitness and health.

"I think it's a great way to teach kids to eat at McDonald's and that McDonald's is good for them," Nestle said. "I think it's brilliant marketing on the part of the company."

Garth Wade is the kindergarten to Grade 12 learning specialist for health and physical education in District 18.

He said the company "circumvented" the district's rules about guest speakers in schools by approaching principals directly, instead of seeking permission from the district.

He acknowledges Ronald McDonald carries a fast-food message to schools, but says children are also learning about being active.

"I'm not disagreeing that there's some sort of hidden message in the sense of trying to promote McDonald's. But in the presentation, there was never one inkling that they were trying to convince kids to go and eat at McDonald's."

Last September, school district 18 became the first in the province to ban junk food from school cafeterias and vending machines.

McDonald's corporate office has not returned calls to CBC News.