Moderate Exercise Reduces Negative Effects of Belly
Fat Leading to Metabolic Syndrome in Seniors
Results with mice were reinforced by the scientists'
study of sedentary older adults
April 24, 2009 It just takes moderate amounts of
exercise to reduce the inflammation in the visceral fat belly fat
that appears to lead to metabolic syndrome, one of the markers most
feared by senior citizens, since it often predicts heart disease and
Type 2 diabetes.
About 47 million adults in the United States
(almost 25%) have metabolic syndrome, and the numbers continue to grow.
The increasing number of people with this condition is connected to the
rise in obesity rates among adults. In the future, metabolic syndrome
may overtake smoking as the leading risk factor for heart disease. (More
about Metabolic Syndrome below news story.)
"In the study, the benefits of exercise were
apparent, even without a change in diet. We saw improvements in insulin
sensitivity, less fat in the liver, and less inflammation in belly fat,"
said Jeffrey Woods, a University of Illinois professor of kinesiology
and community health and faculty member in the U of I Division of
Nutritional Sciences and the Integrative Immunology and Behavior
Program.
Belly fat is particularly dangerous because it
produces inflammatory molecules that enter the bloodstream and increase
the risk of heart disease and diabetes, he said.
"Scientists now know that obesity is associated
with a low-grade systemic inflammation. Obese people have higher levels
of circulating inflammatory markers, such as C-reactive protein (CRP),
which are produced and secreted by fat tissue. This inflammation then
triggers the systemic diseases linked with metabolic syndrome, such as
Type 2 diabetes and heart disease," he said.
In the study, Woods and his colleagues examined the
effects of diet and exercise on the inflammation of visceral fat tissue
in mice. A high-fat diet was first used to induce obesity in the
animals.
After 6 weeks, mice were assigned to either a
sedentary group, an exercise group, a low-fat diet group, or a group
that combined a low-fat diet with exercise for 6 or 12 weeks so the
scientists could compare the effects in both the short and long term.
"The surprise was that the combination of diet and
exercise didn't yield dramatically different and better results than
diet or exercise alone," said Vicki Vieira, the lead author of the
study.
"Unexpectedly, the only significant increase from 6
to 12 weeks in belly fat - the type of fat that triggers these
inflammatory diseases - was in the mice who were sedentary, which
suggests that exercise is an effective behavioral approach to reduce the
accumulation of visceral fat even when fat in the diet is high," she
said.
Woods says that is a promising finding. "The
benefits of exercise were apparent even if the animals were still eating
a high-fat diet. That tells me that exercise could decrease or prevent
these life-threatening diseases by reducing inflammation even when
obesity is still present."
"The good news is that this was a very modest
exercise program. The mice ran on a treadmill only about one-fourth of a
mile five days a week. For humans, that would probably translate into
walking 30 to 45 minutes a day five days a week," he noted.
"Even if you struggle with dieting, we believe you
can still reduce the likelihood of developing obesity-related
inflammatory diseases, such as Type 2 diabetes and heart disease, by
adding a modest amount of exercise to your life," said Woods.
These results were reinforced by the scientists'
study of sedentary older adults published in a recent issue of Brain,
Behavior and Immunity (BBI).
In that 10-month study, one group of sedentary
older adults participated in three 45- to 60-minute cardiovascular
exercise sessions per week, while another group focused on exercises to
improve non-cardiovascular flexibility and balance for 75 minutes twice
a week.
"At the end of the study, the 'cardio' group had
lower levels of C-reactive protein (CRP), less belly fat, and improved
general fitness than the 'flex' group," said Ph.D. candidate Vieira.
"The lower CRP levels were partially mediated by
the reduction in trunk fat," she explained.
Background
The mouse study was published in the American
Journal of Physiology, Endocrinology and Metabolism. Co-authors are
V.J. Vieira, R.J. Valentine, K. Wilund, N. Antao, T. Baynard, and J.A.
Woods, all of the University of Illinois. The study was funded by the
National Institutes of Health and the American College of Sports
Medicine.
Co-authors of the BBI study are V.J. Vieira, L. Hu,
R.J. Valentine, E. McAuley, E.M. Evans, T. Baynard, and J.A. Woods of
the University of Illinois. Funding was provided by the National
Institutes of Health.
What Is Metabolic
Syndrome?
Metabolic syndrome
is the name for a group of risk factors linked to
overweight and obesity that increase your chance for heart disease
and other health problems such as diabetes and stroke. The term
metabolic refers to the biochemical processes involved in the bodys
normal functioning. Risk factors are behaviors or conditions that
increase your chance of getting a disease. In this article, heart
disease refers to
coronary heart disease.
The five conditions
listed below are metabolic risk factors for heart disease. A person can
develop any one of these risk factors by itself, but they tend to occur
together. Metabolic syndrome is diagnosed when a person has at least
three of these heart disease risk factors:
● A large
waistline. This is also called abdominal obesity or having an apple
shape. Excess fat in the abdominal area is a greater risk factor for
heart disease than excess fat in other parts of the body, such as on the
hips.
● A higher
than normal triglyceride level in the blood (or youre on medicine
to treat high triglycerides). Triglycerides are a type of fat found in
the blood.
● A lower
than normal level of HDL cholesterol (high-density lipoprotein
cholesterol) in the blood (or youre on medicine to treat low HDL). HDL
is considered good cholesterol because it lowers your chances of heart
disease. Low levels of HDL increase your chances of heart disease.
● Higher than
normal blood pressure (or youre on medicine to treat
high blood pressure). Blood pressure is recorded as two numbers,
usually written one on top of or before the other, such as 120/80. The
top or first number, called the systolic blood pressure, measures the
pressure in the bloodstream when your heart beats. The bottom or second
number, called the diastolic blood pressure, measures the pressure in
your bloodstream between heartbeats when the heart is relaxed.
● Higher than
normal fasting blood sugar (glucose) (or youre on medicine to treat
high blood sugar). Mildly high blood sugar can be an early warning sign
of diabetes.
The more of these
risk factors you have, the greater your chance of developing heart
disease, diabetes, or a stroke. In general, a person with metabolic
syndrome is twice as likely to develop heart disease and five times as
likely to develop diabetes as someone without metabolic syndrome.
April 24, 2009 It just takes moderate amounts of
exercise to reduce the inflammation in the visceral fat belly fat
that appears to lead to metabolic syndrome, one of the markers most
feared by senior citizens, since it often predicts heart disease and
Type 2 diabetes.
