Are physically active kids better learners? This is Part 1 of The Globe's series on children's fitness and education. Read Part 2 and Part 3.

Canadian children are suffering an epidemic of inactivity that contributes to rising obesity rates and weaker academic performance.

One in four Canadian children is overweight or obese, and just 7 per cent get the recommended 60 minutes a day of exercise, according to Statistics Canada.

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School seems the best place to inject activity into the daily lives of children and promote healthy lifestyles. But despite efforts by provinces to serve better food in school cafeterias and bolster physical education from kindergarten to Grade 12, obesity rates are still climbing.

The mistake of educators may have been to treat physical education like a second-tier academic add-on. Research shows that exercise improves concentration, attention span and mood. Recent U.S. studies show that overweight children get lower grades than their healthier peers.

Last week, Ontario struck a panel tasked with reducing childhood obesity rates by 20 per cent over five years. Although the initiative was welcomed by educators and health professionals alike, the panel's mandate is ambitious. That kind of success in reducing obesity would be unprecedented, according to Jill Hamilton, director of the Hospital for Sick Children's obesity management program.

Obese children in the Toronto area are often referred to her clinic. Her first step is to determine through a bevy of blood samples and tests whether a hormonal imbalance is causing a child to gain weight. She's noticing that more and more often hormones aren't to blame.

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"The numbers are certainly increasing and we don't find any particular reason," she said.

That's one reason she feels Ontario's goal is admirable, but lofty: Obesity isn't caused by any one thing. Genetics, fast food, overworked parents, video games and the Internet are among the culprits.

It will take multiple interventions aimed at different aspects of healthy living to have an impact, and in this way obesity is a lot like smoking, according to Mark Tremblay, an obesity and activity researcher at Children's Hospital of Eastern Ontario in Ottawa.

Any one intervention on its own, such as healthier cafeteria food, might not have a measurable effect. But that doesn't mean it's not working, according to Dr. Tremblay. "At some point there's a straw that breaks the camel's back."

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He points to the decades of billboard campaigns, school visits by public health nurses, alarming labels and the like that helped smoking rates drop from nearly 50 per cent in 1965 to just over 20 per cent in 2010.

Many initiatives struggle just to get off the ground. This fall, Ontario launched a food and beverage policy that banished high-calorie, deep-fried foods from school cafeterias, only to see cafeteria profits plummet as students began crossing the street to their local fast-food joint.

Ontario's efforts to inject physical activity into the school day also have been problematic. Elementary schools have been required to offer 20 minutes of daily physical activity (DPA) to students since 2005. But according to the results of People for Education's annual school survey, which will be released next week, educators are struggling to fit exercise into an "already packed school day." Principals listed insufficient equipment, space, teacher training and commitment as the barriers.

One approach is to make physical education mandatory at every grade level. That's what Manitoba did in 2007, and this fall it will conduct a survey to see if student attitudes toward their health and physical activity have changed since the legislation was brought in.

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Meanwhile, teachers across the country are finding creative ways to teach their kids about healthy living. One high-school teacher in Vancouver is training at-risk youth to run marathons and getting them to stay in school.

Tad Pfupa, a Grade 8 student at Camilla Road school in Mississauga saw his math grades climb from the low 70s into the 80s when he joined the school's fitness program, called ACE, which involves at least 30 minutes of exercise each day.

"I can get through an entire day now without getting fidgety. Before, that would be so hard," he said. "And I don't get sent down to the office really any more."

A lot of Canadian children aren't getting 30 minutes of physical activity a day at school. The Globe and Mail compared levels of activity required by provincial education ministries across Canada and they vary from as little as none for some high school students to 60 minutes a day.

Dr. Tremblay is developing a measure he calls physical literacy, one that tracks not only fitness but motor skill development, behaviour and knowledge of healthy living. He'd like to see such measures become a component of standardized testing and given the same scrutiny as literacy and numeracy.

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"A school can be doing a miserable job or a fantastic job and it just doesn't matter," he said. "This is the future health of our kids – how can we not prioritize that?"

With research from Rick Cash

Interactive: Click here to explore the problems a generation of sedentary children has created for educators, check out some schools that are working on solutions and share your thoughts and stories