"Healthy" waist may be a bit bigger for black women

NEW YORK (Reuters Health) - The definition of a ‘healthy’ waistline may have a bit more wiggle room for African-American women than for white women, a new study suggests.

As it stands, men are considered to have abdominal obesity when their waistline tops 40 inches; for women, the threshold is 35 inches. Abdominal obesity, in turn, raises a person’s risk of diabetes and heart disease.

Another way to look at the weight-health question is through body mass index (BMI) -- a measure of weight in relation to height. People with a BMI of 30 or higher are considered obese, and they generally have a higher risk of diabetes and heart disease than thinner people.

But in the new study, researchers found that African-American women might have somewhat higher thresholds for a risky waist size and BMI.

For the study, reported in the journal Obesity, researchers tried to estimate the BMI and waist size that best separated people at relatively high risk for diabetes and heart disease from those at lower risk.

High risk in this case meant having two or more risk factors for those diseases -- such as high blood pressure, high cholesterol or elevated blood sugar.

For white women and men of both races, a BMI of about 30 was the threshold -- the same as the standard value. But among black women, it was 33.

The same pattern was seen when it came to waist size. For men and white women, the waistline thresholds in this study were close to the 40-inch and 35-inch standards, respectively.

Among African-American women, however, the “high-risk” waistline was slightly more than 38 inches -- 3 inches larger than the standard threshold.

That suggests that the average black woman can be heavier than her white counterpart before her risk for heart disease and diabetes start to climb dramatically.

Still, more research is needed to show that, according to lead researcher Dr. Peter T. Katzmarzyk, a professor at the Pennington Biomedical Research Center in Baton Rouge, Louisiana.

He explained that this study looked at participants at point in time only, and studies following people over time -- looking at how different levels of obesity predict the odds of developing heart problems and diabetes -- are now necessary.

“We do not want to make too many practical implications at this point,” Katzmarzyk told Reuters Health in an email.

He also stressed that the findings do not mean that African-American women with a BMI below 33 or a waistline under 38 inches have “no risk” of obesity-related health problems.

“What the study does show is that there is a strong relationship between obesity and risk factors in white and African-American men and women,” Katzmarzyk said. “This relationship is robust in all groups, so no one is immune from the effects of obesity.”

The findings are based on 6,476 adult volunteers who had their weight, blood pressure and other health factors measured as part of a larger study of obesity, lifestyle and chronic disease risks. Just over 2,400 participants were African American.

It’s not clear why there was a racial difference among women but not men, according to Katzmarzyk.

One possibility, he said, is that white and black women have differences in the specific areas of the body that fat tends to accumulate -- and men may not have those differences.

SOURCE: Obesity, online January 6, 2011.