To take the pulse of the nation – and figure out how much Canadians weigh – the federal government conducts tens of thousands of interviews each year.

For the 2013 Canadian Community Health Survey, about 65,000 people were asked a long list of questions about their health. Weight and height answers were used to determine body mass index (BMI), classifying people as underweight, normal weight, overweight or obese.

For Canadian Geographic’s April issue, cartographer Chris Brackley mapped provincial obesity and overweight rates among people 18 and older. To better understand the data, we talked to Statistics Canada analyst Amanda Wright.

Q: How is this information collected each year?
A: It’s collected through telephone and personal interviews. That’s in all provinces and territories. In Nunavut, it represents the 10 largest communities.

Q: How accurate is self-reported weight information?
A: There’s been a bias that was determined. Women tend to underreport their weight, while men tend to over report their height.

Self-reported data that we publish is very good for looking at comparisons and trends over the years, because people are going to under report or over report their height and weight at similar amounts. It’s really good for gauging the trend that’s going on. For trends for a large population, this is the best way to get at that data.

Q: What do you notice when you look at the 2013 overweight and obese rates?
A: If we’re just comparing it to the previous year, the national rates of overweight and obese combined as a category, is about the same as in 2012. If we break it down by male and female, the rates for women for this combined category have remained stable since about 2009. For men, it was an increase in 2013, over 2012.

Q: How do the provinces compare?
A: The rates were lower than the national average in B.C. only in 2013 and they were higher in Newfoundland and Labrador, PEI, Nova Scotia, New Brunswick, Manitoba, Saskatchewan and Yukon. The remaining provinces were about the same as the average.

Then we can break it down by just looking at obesity rates, so nationally the obesity rates were about the same as in 2012. More men than women were obese in 2013 and provincially, Ontario and B.C. were lower than the national average.

Q: What about overall trends?
A: It’s the obesity rates that have increased over the last 10 years. The overweight rates have remained about the same – around 33 or 34 per cent (nationally).

Q: Do you look at why provinces remain above or below average?
A: We can’t say why but you can look at it in the context of other health behaviours. You can look at other things like health conditions, like high blood pressure and diabetes and health behaviours like whether or not they’re eating at least five portions of fruit and vegetables per day, the proportion of people that are physically active.

Newfoundland and PEI were two provinces that were higher for their obesity and their overweight rates than the national average. They had higher high blood pressure rates, they had higher diabetes rates, they had lower fruit and vegetable consumption and they had lower physical activity (as moderate or active). Whereas BC, it was pretty much the opposite situation.