'Healthy immigrant' effect fades after decade: report

Recent immigrants to Canada are less likely to be overweight, but people tend to pack on the pounds within a generation, a new report suggests.

Newcomers who have been in Canada for 10 years or less were less likely to be overweight compared to those who immigrated longer ago, Statistics Canada reported Tuesday.

• INDEPTH: Obesity

"The higher prevalence of overweight among long-term immigrants supports the notion that a 'healthy immigrant' effect fades within a decade for all ethnic groups," said the authors of the report, called Obesity, Overweight and Ethnicity.

A shift toward more of a "western" diet and couch-potato lifestyle may explain the differences.

• INDEPTH: Diet primer

As more Canadians become overweight, and the country becomes more diverse, ethnic analysis is called for, particularly since type II diabetes seems to affect some groups such as aboriginals disproportionately, the report said.

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Understanding why different ethnic groups tend to gain excess weight may help to identify those at high risk and target prevention strategies, the report concluded.

Previous studies have found that although immigrants to North America are less likely to be overweight, within two or three generations, the prevalence of excess weight often exceeds that of non-immigrants.

Dr. Mark Tremblay, senior scientific advisor for health measurement at Statistics Canada in Ottawa, and his colleagues used self-reported ethnicity and weight data from 130,000 people aged 20 to 64 from 2000/01 and 2003.

The self-reported prevalence of obesity was:

• 3 per cent for East and Southeast Asians.
• 17 per cent for whites.
• 28 per cent for aboriginal people living off reserve.

The low prevalence of overweight and obesity among East and Southeast Asians may be deceptive though, the report's authors noted, since research suggests Asians have a greater proportion of body fat than their white counterparts.

In fact, metabolic disorders such as diabetes may appear among Asians with a BMI as low as 23, even though the at-risk threshold is set at 25. Body weight guidelines may not be suited to identifying health risk equally for all ethnic groups, the analysts added.