So, you've just polished off a meal high
in fat, and now you're feeling guilty? Wait
an hour or two, then get a little exercise,
and you can reverse the potential damage to
your arteries, a new study suggests.
And you don't even have to head to the gym
for that exercise. "We're talking about
a walk, we're not talking about changing your
clothes and sweating," said Janet P.
Wallace, a professor of kinesiology at Indiana
University, and lead investigator for the
study.
The study, coincidentally, follows another
study published earlier this month in the
Journal of the American College of Cardiology
in which researchers found that eating just
one piece of carrot cake high in saturated
fat and drinking a milkshake can reduce the
body's ability to protect itself against heart
disease.
The fat in the cake and shake, it seems,
reduces the ability of the body's "good"
cholesterol -- the high-density lipoprotein,
or HDL -- to do its job --protecting the inner
lining of the arteries from inflammatory substances
that promote vessel-clogging plaque.
According to Wallace, after a fatty meal,
arteries lose their ability to expand in response
to an increase in blood flow. The effect peaks
four to six hours after eating -- usually
just in time for your next meal. So, four
hours after a fatty meal, your arteries look
like those of a person with heart disease,
she said.
"That post-meal period is a hot topic
among all the researchers in heart disease,
diabetes and obesity," Wallace said.
"That period sets up the environment
for the artery to be unhealthy. And when the
artery is unhealthy, that is when it leads
to heart disease, insulin resistance and other
problems."
To see if exercise could make a difference,
Wallace and her colleagues studied eight healthy
25-year-olds, looking at three scenarios.
Each of the participants -- five men and three
women -- completed all three scenarios. They
ate a low-fat breakfast. They ate a high-fat
breakfast. And they ate a high-fat breakfast
followed two hours later by a 45-minute walk
on a treadmill at a moderate pace. The high-fat
meal contained about 48 grams of fat and the
low-fat one actually had no fat; each consisted
of about 940 calories.
The researchers used a blood pressure cuff
to measure blood flow in the brachial artery,
located in the arm, before and after each
scenario. "The brachial artery represents
what is going on in the arteries of the heart,"
Wallace said.
After the high-fat meal alone, the brachial
artery dilation dropped from 6 percent to
4 percent, Wallace said. "The ideal range
is about 6 to 10," she said. "A
range of 3 to 5 is not good."
After the low-fat meal, dilation went from
6 percent to 6.5 percent, a slight improvement.
But, "after the high-fat meal and exercise,
it went from 6 percent (before the meal) to
8 and a half percent," she said.
"Exercise does great things, and this
obviously shows exercise is very effective
in counteracting that high-fat meal,"
Wallace added.
The study results were published in the September
issue of the European Journal of Applied
Physiology.
Next, Wallace hopes to study the effect of
exercise before a high-fat meal. "I
think we will find it works as well."
She emphasized that her research isn't meant
to encourage people to indulge in high-fat
fare. But she's realistic: "There are
people who are going to eat high-fat meals,"
she said.
If you're a fatty-food fan, Wallace suggests
some exercise -- after getting your doctor's
OK.
But Jeannie Moloo, a Sacramento, Calif.,
registered dietitian and a spokeswoman for
the American Dietetic Association, offered
a caveat about the study: "We need to
keep in mind the results apply only to the
population investigated and that was young,
healthy and physically active adults. The
small number of subjects, only eight, makes
it difficult to tell if there are differences
in responses between men and women."
And Moloo, like Wallace, cautioned that the
research isn't an excuse to indulge in fatty
foods.
