Canadian adults who live in rural areas are more likely to be obese than city dwellers, Statistics Canada reported Tuesday.

In 2004, 20 per cent of adults who live in large Canadian cities were obese, compared to 29 per cent in smaller centres.

The national average for obesity was 23 per cent.

The size of the city also mattered: as the size of the city grew, the likelihood of being obese fell.

In St. John's the number of obese people was 36 per cent, compared to 16 per cent in Toronto and 12 per cent in Vancouver.

The wider use of cars in rural Canada may be partly to blame, said Dr. David Lau, an endocrinologist in Calgary.

"In the larger cities, people are relying more and more on public transportation," said Lau. "For that, they have to walk a few feet here and there, and that may explain the difference."

Physical activity challenge

The trend persisted after researchers accounted for immigrants, who tend to be less overweight and settle in larger cities.

Research suggests people who are poorer tend to be more obese, as are men with higher incomes, said Dr. Arya Sharma, scientific director at the Canadian Obesity Network in Hamilton, Ont.

The disparity reflects differences in physical activity levels and food choices, Sharma said.

The 25 per cent of adults who are already obese need more treatment options.

"We need to get our act together," on prevention he said, since it is so difficult to lose weight and keep it from creeping back. Convincing residents in smaller urban and rural areas to be more active is part of the challenge, public health experts said.

The urban-rural split did not hold for Canadian children, the agency's researchers found.

Nationally, the proportion of two- to 17-year-olds who were overweight or obese was comparable regardless of the size of the community, with one exception.

In Alberta, people aged two to 17 who lived in census metropolitan areas were less likely to be carrying excess weight than those who did not.

The results are based on actual measurements of heights and weights.