Lifestyle lessens effect of obesity on heart risk

For a given level of obesity, Inuit men and women living in Greenland are healthier than those who have migrated to Denmark, Danish researchers have found.

The stay-at-home Greenlanders are still living a relatively traditional lifestyle, and they had lower blood pressure, lower levels of the blood fat triacylglycerol, and less insulin resistance - an indicator of diabetes risk - according to a report in the American Journal of Clinical Nutrition.

"These findings indicate that lifestyle factors play a major role for observed differences in the levels of risk factors for cardiovascular disease at a given level of obesity," Dr. Marit E. Jorgensen of the National Institute of Public Health in Copenhagen and colleagues conclude.

However, they add, their study was unable to tease out which lifestyle factors might be responsible for these differences.

Jorgensen's team compared obesity and heart disease risk factors among 1,316 Inuits living in Greenland and 995 who had migrated to Denmark. The Inuit lifestyle in Greenland has changed significantly since the 1950s, when most survived by hunting and fishing, the researchers note, but Inuits continue to hunt and fish for recreation, and traditional foods such as seal and fish still compose up to a quarter of their diet.

There are currently about 7,000 Inuit living in Denmark, the researchers add. "This group of migrants is well integrated into Danish society and has a lifestyle similar to that of the general population of a Western industrialized country," they explain.

As noted, Inuits living in Greenland had more moderate risk factors for heart disease for any degree of obesity than those in Denmark. However, the researchers found, women migrants had higher levels of HDL or "good" cholesterol than those still living in Greenland.

One explanation for the findings could be that the traditional diet, which is rich in omega-3 fatty acids found in fish, could have an effect on how body fat influences heart disease risk, the researchers note.

Another possibility is that men and women migrants may have accumulated more abdominal fat - which is specifically linked to heart disease - while those living in the Arctic might have their fat distributed more evenly throughout the body to protect themselves from the cold, although this theory would be extremely difficult to test.

The researchers conclude: "The findings indicate that lifestyle factors modify the cardiovascular disease risk associated with obesity."

SOURCE: American Journal of Clinical Nutrition, July 2006.