TORONTO -- Neighbourhoods with a high number of fast food restaurants are no place for the weight conscious, a new study suggests.

The research reveals that the average body mass index of Canadians living in areas with a high density of fast food outlets is higher than the average BMI of people who live in neighbourhoods with more full-service restaurants.

The work was conducted by scientists at the University of Western Ontario, in London, and published in the Canadian Journal of Public Health.

Some earlier studies done in the United States have revealed similar findings, as have a couple of small studies looking only at children in two different centres in Canada. The authors say this paper is the first to show the possible link in the Canadian adults based on individual-level data.

And they say the finding could be used to justify government action, whether that's zoning bylaws aimed at restricting the density of fast food outlets or requiring fast food restaurants to post calorie counts for the food items they serve.

But an expert who treats patients battling obesity says he found little new in the study. And Dr. Yoni Freedhoff of the Bariatric Medical Institute of Ottawa says the weight differences identified by the study are not enormous.

"This is a small drop in a very large bucket and while I am all for affecting and attacking all drops, there are a lot of bigger drops we've got to hit before we start worrying about zoning fast food," says Freedhoff.

The researchers used data gathered in the 2007-08 Canadian Community Health Survey, charting the average individual BMIs in neighbourhoods against a database of restaurants found across the country.

A study of this type cannot prove cause and effect, so the researchers cannot say that living near fast food restaurants is contributing to the higher weights of people in those areas. It could also be that fast food restaurants are located in less affluent neighbourhoods, where people have limited capacity to buy healthier but more expensive food focusing on fresh fruits and vegetables.

The study found more fast food outlets was associated with higher weights and more full-service restaurants was associated with lower weights.

In either case the effect small. For instance women of average height who lived in fast-food plentiful neighbourhoods weighed on average 1.14 kilograms more than women who lived around fewer fast food outlets. And men who lived in areas where there were a lot of full-service restaurants weighed on average three kilograms less than men who did not.

Freedhoff says he looks for information that will help his patients when he reads studies. With this one, the finding underscores something they would already have heard.

"Your kitchen is your friend when it comes to weight and restaurants are places to try to minimize and to use for occasions," Freedhoff says.

"I think one thing that's incontrovertible in regards to weight is that people who eat out in restaurants a lot more frequently tend to struggle more with their weight and that as a society we go out to restaurants a lot more than we ever used to."