OTTAWA — Adults who live in cities are less likely to be obese than those living in outlying areas, says a new report from Statistics Canada.

The agency said 20 per cent of residents aged 18 or older who lived in large centres were obese in 2004, compared with 29 per cent of those who lived outside a metropolitan area.

And as the size of the city increased, the likelihood of being obese fell, said the report released Tuesday.

In areas with a population of at least two million, such as Toronto, Montreal and Vancouver, 17 per cent of adults were obese.

The comparable figure for areas with a population of 100,000 to two million was 24 per cent, and in urban centres with populations of 10,000 to 100,000, 30 per cent of adults were found to be obese.

The national average for obesity among adults was 23 per cent, or 5.5 million Canadians.

Levels of physical activity are behind the urban-rural split, says obesity expert Dr. Arya Sharma, director of the Canadian Obesity Network in Hamilton.

Reliance on cars in suburban and rural areas is the main culprit, he said, while nutritional factors are less crucial.

"The amount of physical activity that you can get into your day is extremely important in terms of obesity prevention," Sharma said.

"People who live in the countryside are less likely to walk and less likely to ride a bicycle than people in urban centres.

"Nutrition is contributing to the overall obesity problem, but I don't think it is contributing to the rural-urban split.''

The study found fewer urban-rural obesity differences among the almost 9,000 children and adolescents surveyed, which Sharma said could be explained in part by the fact children in both settings get driven around a lot.

The report also noted that while obesity rates remained stable between 1979 and 1992, by 2004 they had risen notably -- particularly among young men who were former smokers, and men of higher socio-economic status.

"This is kind of a surprise, because we think of obesity as affecting the lower socio-economic groups. Is it that people with higher economic status have more desk jobs? Perhaps stress levels are different, and times spent for recreational activity is different," Sharma said.

Margot Shields, senior analyst with Statistics Canada said the body mass index or BMI of all those surveyed was calculated after each was weighed and their height measured. A BMI of 30 and above is considered obese.

Shields said that while the report shows some correlation between obesity and the level of physical activity, a study on links between nutrition and obesity will be released sometime next year.

Wendy MacDonald, executive director of Ottawa's Pinecrest-Queensway Health and Community Services, said obesity is a growing for her suburban clients, many of whom are immigrants struggling to read food labels and prepare meals with unfamiliar ingredients.

"About 50 per cent of our clientele are immigrants and they are also struggling economically," MacDonald said.

"Money for exercise programs and recreation is often not there. We definitely see a link between a low income and obesity."

Food banks and numerous fast food restaurants contribute to poor eating, she said.

Meanwhile, a poll on fitness released Tuesday suggests most Canadians want to take steps to lose weight and increase their strength.

One in four said they want to lose weight, while 13 per cent said they want to become more fit, and 26 per cent had both goals in mind. Just over a third said neither are goals.

Decima surveyed 1,012 Canadians in June. Results are considered accurate to within plus or minus 3.1 percentage points, 19 times out of 20.