BMI differences: The immigrant equation

The obesity problem plaguing Canadians is a story heard frequently these days. For Katerina Maximova, making connections between the rising body mass index, or BMI, among native-born Canadian versus immigrant children has been the focus of a recent study.

In a journal article recently published in the Annals of Epidemiology, Maximova, an assistant professor with the School of Public Health at the University of Alberta, analyzed data from approximately 6,400 low-income children in an inner-city Montreal neighbourhood who were followed for more than five years. Within this group, 104 countries of origin were represented, which Maximova says was crucial to understanding how BMI changes for immigrant children as they grow.

"We analyzed the data to focus on changes in BMI exhibited in immigrant children," says Maximova. The longitudinal data revealed new insights on the health of these children; up to this point, most data collected had been on immigrant adults.

"What we already know is that immigrant adults are in better health on arrival than native Canadians, and we call this the 'healthy immigrant effect,'" said Maximova. "What we wanted to know is if this healthy advantage is extended to children of immigrants."

The study covered new-to-Canada immigrant children, second-generation immigrants—children born in Canada whose parents immigrated to Canada—and native-born Canadian children between the ages of nine and 12 years. These groups were further sorted by cultural background like European, Asian, and South American. All of the children came from similar depressed socio-economic backgrounds.

The data revealed striking indicators: The healthy weight advantage that new-to-Canada immigrant children enjoy is not evident in second-generation immigrants or native-born Canadian children. "The advantage is lost with each successive generation that lives in Canada," says Maximova.

"The data suggests that, the longer you live in Canada, the more likely it is that you'll adopt an unhealthy lifestyle."

As time goes on, she says, the BMI of immigrant youth begins to converge with the BMI of the unhealthier native-born Canadian youth. This suggests a need for more resources to be directed towards low-income communities where immigrants often settle in order to develop environments that support healthy choices.

"For instance, if immigrant children move into neighbourhoods where there are playgrounds for them to be active, few fast food outlets to tempt them to make less healthy choices, and people around who are eating healthy and exercising as part of their social environment, I think we will see a difference on their BMI," says Maximova.

"New immigrants want to adopt Canadian ways when they arrive, particularly youth. Within this specific age group, the pressure to fit in to Canadian cultural norms is multiplied even further," she adds.