You do have to wonder where it stops, though. "Apple juice can have just as many calories per ounce [as pop]" Prof. Cawley says. "Why aren't you taxing the Xbox for making video games, or HBO for making television more interesting?"
A corny example might be a guide
Still some economists and obesity researchers argue that taxing sugar-rich foods is a small step toward correcting an imbalance already created by agricultural subsidies, particularly for corn grown by U.S. farmers.
That subsidy led to overproduction, Prof. Cawley says, so producers made corn-fructose, one of the cheapest and most health-harming forms of sugar, the stuff that sweetens soda pop.
In Canada, where subsidies play a much smaller role, research and development have focused on producing and delivering food cheaply, without much consideration of the health impacts. "The problem is that the least high-quality, the most calorie-dense foods are also the cheapest," says Diane Finegood, who studies obesity at Simon Fraser University.
But if agricultural subsidies and taxes have changed how we eat, why can't a similar approach be used to make us eat better?
"If these incentives were used in a more sensible way, with health objectives in mind, they could achieve a lot," says Franco Sassi, a leading economist on the OECD report.
A revamped food policy might consider how to create incentives for farmers to grow local fruits and vegetables, Prof. Faulkner adds, with revenue insurance to help protect them from transportation delays on produce with a shorter shelf life.
Tax incentives, in general, are an underused method of fighting obesity, Dr. Sassi says. But it's not as simple as handing out cash to parents who send their kids to hockey, as the Harper government is doing - one study showed the majority of families benefiting from the tax break would have been headed to the rink anyway.
Get families to vouch for their own health
Giving money directly to Canadians to get healthy is what Mr. Seeman and Mr. Luciani promote. Their book makes the case for a healthy-living voucher, similar to an education voucher in the U.S. - a $5,000 payment to each Canadian over 16 to design an individual health plan, following guidelines and in consultation with their doctor, who could bill the province extra for the service.
Such a program, Mr. Seeman suggests, would allow for individual solutions to the various reasons people gain weight. Some might use the money for personal trainers or nutritional consultants; others might receive mental-health counselling. If all went well, gyms and grocery stores would spring up in low-income areas, as residents pool funds and offer new markets for neighbourhood facilities.
Of course, the program is complicated: How do you prevent people from taking the money and doing nothing? How do you enlist the support of an already overworked medical community? And how do you fund it? The book estimates it would cost up to 4 per cent of provincial budgets. (For starters, Mr. Seeman proposes spending less money educating the public on what they already know. The payoff comes later, with a healthier population.)
But as the OECD report agrees, the advantages are also clear: It allows for individual autonomy and recognizes the complexity of obesity.
However, most experts suggest the best programs will tackle the problem from different angles. Prof. Faulkner finds the voucher concept promising, but also points out that to reduce smoking, "we threw everything at the problem. We tax cigarettes, but I can still call a helpline to get personal help to quit smoking. That's what we need to do with obesity."
All these measures take time to produce results - requiring patience, a quality typically lacking in governments, especially minority ones. One good place to start would be to require, as Britain has, that every provincial and federal public policy be considered for its impact on health.
To fight obesity takes more sweeping changes than TV commercials and healthy cafeteria food. And certainly, Mr. Seeman says, the image of a man drinking fat is the last thing that will make us thin.
He's speaking from experience: He recalls, after a difficult struggle with his own weight, standing in a New York subway aghast at a poster of fat glugging into a glass, sponsored by the city's department of health and mental hygiene.
"That ad jarred me," he says, but it certainly would not have helped the depression that had complicated his health, for which he'd sought counselling.
In the end, as his book advocates, he found his own way: He took up boxing.
Erin Anderssen is an Ottawa-based feature writer for The Globe and Mail.