Overweight people might
be pleased with a new U.S. study that shows they do not need to lose
weight to improve the cholesterol levels in their blood. However,
they must exercise.
But, low intensity exercise seems
to be just as good as high intensity as long as there is enough of
it.
For the first time, researchers at Duke University in North
Carolina have shown that exercise without weight loss has a positive
impact on cholesterol.
Cholesterol is an energy-rich fat that nourishes body tissues as
it is carried through the blood attached to protein particles. High
levels have been linked to heart disease. It can collect on the
inner walls of blood vessels, reducing or blocking the flow of
blood.
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Dr. William Kraus
Duke
University Medical Center photo |
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In The New England
Journal of Medicine, the Duke University team shows that
overweight, sedentary men and women with high cholesterol levels
improved their cholesterol profile when they exercised on stationary
bicycles or treadmills for eight months, doing the equivalent of
jogging 32 kilometers a week. This was true, despite maintaining
their original weight as instructed.
"Although we do not advocate not losing weight, one should not
focus on weight loss as a major benefit of an exercise program," the
research leader, physician William Kraus said. "Be assured
individuals who don't lose weight with exercise are still obtaining
benefit,"
Dr. Kraus also says those in the group that performed the
equivalent of running 32 kilometers a week improved their
cholesterol profile more than another group that exercised 60
percent as much, but at the same intensity. A third group that
exercised even less had the least improvement. But a fourth that did
not exercise at all had worse cholesterol than at the start of the
study.
"Any exercise is better than none, but more quantity per week,
not necessarily more intense exercise, is better than less exercise
with respect to improving your cholesterol profile," Dr. Kraus said.
To heart doctor Alan Tall of Columbia University in New York, the
study provides a ray of hope for people who find it easier to
exercise than to lose weight.
"In previous studies where
those beneficial changes in the blood were seen, they were
correlated pretty well with loss of body fat," Dr. Tall said. "But
in this study, they were able to detect pretty large effects even
without body weight loss.
The improvement was not necessarily in lower levels of the bad
form of cholesterol known as LDL, but changes in the number and
density of the size of the LDL particles. The researchers showed
that increasing amounts of exercise increased the particle sizes,
making them fluffier. Dr. Kraus at Duke University says this is
considered healthier, possibly because they break up more easily in
the blood or do not get trapped in small crevices in blood vessels.
He says the study shows it is better to measure the bad
cholesterol this way rather than measure its total amount.
"Many clinicians are confused because they will see two patients
come in with the same LDL cholesterol with very different
cardiovascular outcomes. One has heart disease and one does not,"
Dr. Kraus explained. "If one is able to look at the particle size
and number, often those differences become clear that the individual
with heart disease is carrying his cholesterol in smaller, dense
particles.
To keep it all very simple, Dr. Kraus recommends overweight
people cover 32 kilometers a week either by jogging or walking or
doing three and a half to four hours of some other exercise.
