Naturally there's something amusing about the story: an Ottawa elementary school is restricting students to a single slice of pizza at their weekly pizza lunch.

"Hey, kids," you can imagine teachers announcing, "enjoy yourselves and eat to your hearts' content! Except please only eat the arugula to your hearts' content. The pizza is being rationed."

And naturally, this joy-draining food rule arises from regulation that was supposed to not only make kids healthier, but also "enhance students' social and emotional well-being" — the Ontario school nutritional guidelines introduced in 2011.

Sure, it's funny to picture Ontario educators turning into the Soup Nazi of Seinfeld fame, shouting "No pizza for you!" at terrified six-year-olds. But it's not so funny when you realize that there's a serious problem here, one that follows a rather universal principle: when the government or administrators impose overly prescriptive lifestyle regulations on schools — and therefore school kids — you end up with absurd results that make kids worse off.

Trusting schools to implement the rules

That's true whether we're talking about pizza quotas or rules designed to protect personal space that end up prohibiting affectionate kindergartners from hugging their friends. (Yes, no-hugging and no-hand-holding rules have really been put in place in some elementary schools in Canada and Australia.)

When legislators introduce these regulations, they often assure us that we don't have to worry about bizarre consequences because schools can be trusted to interpret the rules sensibly. The Ottawa situation reminds us that this isn't always, or necessarily, the case.

For one, it seems the school at the centre of this issue failed to consider the effects these rules will have on students' behaviour. The 2011 nutritional regulations were meant to ban the sale of junk food in schools, but what good does that do if kids just end up spending the day feeling deprived and planning the chocolate bars (or slices of 'za) they'll buy at the corner store as soon as the bell rings?

What's more, it's a particularly bad idea to push restrictive eating patterns (and the idea that certain foods are to be feared) on pre-teens (who can be found in elementary schools such as the one in Ottawa) and adolescents. These kids are at just the age when eating disorders tend to take hold; you can't repeatedly shake a finger at them for reaching for a second slice of pizza, then be surprised when they end up with negative – or even punitive – attitudes about diet and their bodies.

Most experts who work to treat and prevent eating disorders advise that it is counterproductive and potentially harmful to divide food into "good" and "bad" categories – which is exactly what Ontario's school nutrition regulations do. They divvy cafeteria (and fundraiser and pizza day) foods into three categories, the least "healthy" of which can never be sold at all. Sorry, Cookie Monster, some cookies have now been deemed a "never" food.

This sets kids up for a miserable relationship with eating. Which is the opposite of what schools should be doing: using flexible guidelines to offer kids evidence-based nutritional information so that they can make it to adulthood without losing the ability to enjoy and be at peace with food.

Allowing kids to make informed choices

What do I mean by evidence-based? The Ottawa school says that according to the Ontario guidelines, there is too much fat in a couple of slices of pizza. But the science is currently unclear on how helpful it is for people to reduce dietary saturated fat (the kind found in cheese pizza).

Some nutritionists say it's a good idea and helps avoid raising LDL cholesterol (that's the "bad" one), which is believed to contribute to blockages in the heart arteries. Others point to recent reports and meta-studies that fail to show that saturated fat increases the risk of heart disease, but do show that reducing saturated fat can increase the risk of heart disease if the fat is replaced with highly processed carbohydrates.

This is nuanced stuff, and even credible experts disagree. That's why we ought to quit micromanaging kids' diets and instead give them the objective information we do have to help them make their own decisions about what to eat.

In any case, when Ontario education ministry spokesperson Derek Luk weighed in on the pizza-slice question, he gave an answer worthy of a contracts lawyer: "The guidelines don't actually 'restrict the number of servings per child,'" Luk wrote in an email, "they merely provide 'guidelines to boards on the admissible nutritional contents, including fat content, of a serving size that can be packaged and sold as one "meal" in schools.'"

Apparently, all the Ottawa students need do is stop asking for multiple slices of pizza and start asking for multiple lunches instead.

This column is part of CBC's Opinion section. For more information about this section, please read this editor's blog and our FAQ.