[acb-diabetics] article from Diabetic News

[Patricia LaFrance-Wolf]

Good Fat, Bad Fat

Dec 23, 2009 

 

This press release is an announcement submitted by HealthDay, and was not
written by Diabetes Health.

 

FRIDAY, Dec. 18 (HealthDay News) -- Blacks tend to carry around less of a
particularly unhealthy type of abdominal fat than whites, even though they
suffer

more from obesity-linked illness, researchers report.

 

The new finding suggests that body-mass index (BMI) guidelines may need to
be tailored to specific racial groups to better reflect risk, experts say.

 

"The study clearly shows we have these racial differences in body fat, not
just in the type of body fat but where the fat is stored, and these are
important

differences," said study author Peter Katzmarzyk, a professor of population
science at Pennington Biomedical Research Center in Baton Rouge, La.

 

Adipose (fat) tissue is found throughout the body. Subcutaneous adipose
tissue is found just under the skin, while visceral adipose tissue is found
in the

abdominal cavity around the organs.

 

Fat settling around the organs has been linked to development of
obesity-related diseases such as cardiovascular disease and 

type 2 diabetes

, according to background information in the article.

 

But you can't tell just by looking at someone how much visceral fat someone
has. Even a pot belly won't tell you for sure because visceral fat is deep
within

the body cavity, Katzmarzyk said.

 

In the study, researchers used computer tomography (CT scans) and dual-
energy X-ray absorptiometry (DXA) to measure visceral fat in about 1,400
white men

and women and 570 black men and women aged 18 to 84. Participants' height,
weight, BMI and total body fat composition were also measured.

 

At a given body fat percentage, black men and women had lower visceral fat
than white men and women. Conversely, blacks also tended to have higher
subcutaneous

fat than whites. Researchers controlled for age and smoking status, among
other variables.

 

The study appears in the January issue of The American Journal of Clinical
Nutrition.

 

Despite the tendency to have less visceral fat, black Americans are still at
higher risk of dying from obesity-related diseases such as diabetes and
cardiovascular

disease. One explanation for this is that blacks have higher overall obesity
rates overall, Katzmarzyk said.

 

About 31 percent of white adults and 45 percent of black adults are obese,
according to the study.

 

"It's a paradox," Katzmarzyk said. "The fact that white individuals have
more visceral adipose tissue and also have lower rates of obesity-related
disease

is probably because African-Americans have higher rates of obesity overall."

 

The findings also bring up the issue of whether the "one-size-fits-all" BMI
guidelines apply equally to all races, Katzmarzyk said.

 

BMI is a calculation based on height and weight. While a high BMI tends to
mean you also have a lot of body fat, BMI is not a direct measurement of fat

composition. A very muscular person, for example, may have a high BMI but
low body fat composition.

 

A BMI of 30 or above is considered obese, while a BMI of 25 or above is
overweight.

 

Yet previous research has suggested there may be racial variations in what
constitutes a healthy BMI. Diabetes risk for Asians start to rise at a BMI
of

about 23, for example. An optimal BMI for blacks may also vary somewhat,
Katzmarzyk said.

 

"BMI may mean different things for different people," he said. "The study
suggests we may need to think about ethnic-specific thresholds to identify
obesity-related

health risks."

 

Eric Bailey, a professor of anthropology and public health at East Carolina
University and author of Food Choice and Obesity in Black America: Creating

a New Cultural Diet, said BMI recommendations were developed using too
little data on black Americans or other racial and ethnic groups.

 

"We are using BMI as a 'gold standard,' but it needs to be reassessed,"
Bailey said. "It does not necessarily apply to each and every population in
the

same way. Our biology and genetic makeup is slightly different.
African-Americans may be healthier at a different BMI compared to a European
population."

 

Biology aside, Bailey added, there is no question that obesity remains a
serious issue in the black community. Poverty can make affording fresh
fruits and

vegetables and the healthiest cuts of meat more difficult, while unsafe
neighborhoods discourages getting adequate 

exercise.

 

"Many times, sociological, behavioral and cultural issues overrides the
biological," Bailey said. "One-third of African Americans are still in
poverty,

and that influences the types of foods you are able to eat."

 

In another study from the same issue, researchers found that gene variants
that have been implicated in a tendency toward obesity played only a small
role

in a person's BMI.

 

Previous research in twins has suggested as much as 40 percent to 85 percent
of obesity can be blamed on the genes, but the new research shows the
influence

of genetic variants may be much smaller.

 

Researchers at the University of Cambridge looked for 12 genetic markers for
obesity in more than 20,000 participants from the United Kingdom. Those with

at least one gene marker were 3 percent to 14 percent more likely to be
obese than those without the marker, while each additional genetic marker
raised

the risk of obesity by nearly 11 percent.

 

But taken together, the genetic variations accounted for only about a one
percent variation in BMI -- meaning the currently known markers are poor
predictors

of who is at risk for obesity, according to the study.

 

Researchers said it's possible that other, more important obesity-related
gene variants have yet to be identified.

 

* * *

 

Sources:

 

Press release

 

Article abstract 

 

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