Black Girls Don't benefit as much From exercise
In a new study of U.S.
preteen and teen girls, daily exercise was strongly linked to weight and
obesity in white girls but not black girls. Although it's still important to
promote physical activity in all young people, according to the researchers
that may not be enough to prevent black girls -- who have a higher rate of
obesity to
begin with -- from gaining weight.
"I think everyone
would agree we need people to be active. It's not sufficient on its own to
prevent weight gain, but it's really an important part of the equation,"
said Alison Field, who studies weight in adolescents and women at Harvard Medical
School and Children's Hospital Boston.
Still, the new findings
"would suggest that… what we've been recommending may not be the perfect
fit for African Americans," Field, who wasn't involved in the new
research, told Reuters Health.
One possibility is that
along with other lifestyle changes, black girls need to get a lot more exercise
than white girls to start making a difference in their obesity risk, she added.
But it's unclear why that
would be the case, and just how much physical activity they would need.
Field said the results
are "sobering" given that black girls typically are less active to
begin with and getting teen girls involved and engaged in new types of exercise
is particularly challenging.
The findings come from a
second analysis of data originally collected by the National Institutes of
Health, which followed girls in Cincinnati, Berkeley, California and Rockville,
Maryland starting when they were nine or ten years old in 1985.
For the new analysis,
James White of Cardiff University and Russell Jago of the University of
Bristol, both in the UK, used data on physical activity, eating habits, weight
and height from when the girls were 12 and 14 years old.
Physical activity was
measured over three days with a device called an accelerometer, which is kept
in a pouch above the hip and calculates how much time the wearer spends walking,
running or otherwise being active.
At age 14, close to 16
percent of the black girls qualified as obese, compared to just five percent of
white girls.
The researchers found the
most active white 12-year-olds were 85 percent less likely to be obese at the
second reading than the least active. That held up when they took into account
girls' diets and how much time they spent sitting.
But for black girls,
there was no clear link between physical activity at age 12 and obesity at 14.
The study, published
Monday in the Archives of Pediatrics & Adolescent Medicine, included 1,148
girls, split roughly evenly between black and white adolescents.
The
role of genes
Another report published in the same journal found certain genes may affect a person's chance of being obese as a teen and young adult -- but that those influences may also start as early as a few years of age.
Another report published in the same journal found certain genes may affect a person's chance of being obese as a teen and young adult -- but that those influences may also start as early as a few years of age.
Based on 32 small genetic
sequences that have been tied to obesity in adults, people in New Zealand who
had a higher genetic risk were heavier starting at age three, all the way
through age 38 -- the end of the study period.
Researchers led by Daniel
Belsky at Duke University in Durham, North Carolina found that in their
preteens and teens, people were more than twice as likely to be obese if they
had more of those risky gene patterns than average.
That study involved 856
people of European descent -- and the new findings in teen girls question
whether those genes would be equally important in non-whites, Jose Fernandez
from the University of Alabama at Birmingham wrote in a commentary published
with the two studies.
Belsky said one way
researchers can use the new information is to look at how interventions such as
exercise or diet changes affect people with different genes differently.
Genetics certainly isn't
everything, researchers agreed.
"The magnitude of
genetic risks that we're (seeing) in this profile is small," Belsky told
Reuters Health.
"Some of the kids at
higher levels of genetic risk didn't become obese, and some of the kids at
lower levels of genetic risk did become obese."
Field said most genetic
differences related to obesity, including those between whites and blacks, can
be overcome.
"There are certain
people who are more susceptible for obesity and weight gain, but data suggest
that at least for most people, there are things they can do in their lifestyle
to lessen their genetic disadvantage."
Interesting right! This article was shared to me from my Good Friend Jonae!
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