Thursday, March 3, 2011

Comparing U.S. Obesity to Canada

A new report released today by the Centers for Disease Control, “Adult Obesity Prevalence in Canada and the United States,” finds that obesity is more than one third higher in the United States than in Canada.

This conclusion probably surprises no one, given the way “U.S.” and “big” are rapidly becoming synonyms. But is this really a difference between two countries, or is it more of a regional difference, based on regional characteristics such as culture and climate? One way to consider this question is to compare provinces and states along the U.S.-Canada border. I looked specifically at the parts of the border where there are border towns, and compared the Canadian provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, and New Brunswick to the U.S. states of Washington, Montana, North Dakota, Minnesota, Michigan, New York, Vermont, and Maine. Restricting the comparison to the border states and provinces did not change it much. Comparing only the border states and provinces, obesity is still nearly one third higher in the United States than in Canada. The differences you find when you cross the border are more important than the regional differences within either country. That tells you that culinary traditions, which have considerable variation between cities and regions in the United States and Canada, but do not differ quite so much between the two countries, probably are not to blame for recent obesity trends.

There are also ethnic differences between the populations of the two countries, and these matter when it comes to obesity statistics. The study considered ethnic differences, but found that they did not account for much of the difference between the two countries. Comparing only the majority “non-Hispanic white” groups in the two countries, it still found a obesity rate that was nearly one third higher in the United States.

My guess is that the differences are mostly the result of national differences in food regulation, distribution, and advertising. If I had to look for causes, I would probably start by looking for ways to measure the way people view food advertising messages on television.

Obesity is increasing in most of the world, so one way to compare obesity rates is by comparing time periods. Other studies have done this, and one found that obesity rates in Canada are similar to obesity rates in the United States from 18 years earlier.