Visceral Fat Build-Up Is the High Cost of Inactivity
leads to significant increases in visceral fat, and a moderate exercise
regimen can keep this potentially dangerous form of fat at bay,
according to the results of the first randomized clinical trial
evaluating the effects of exercise amount and intensity in sedentary
overweight men and women.
the Duke University Medical Center researchers found that increasing
amounts ofexercise can reduce visceral fat. In terms of overall weight
gain, the patients who did not exercise would gain approximately four
pounds per year, the researchers said.
the form which accumulates around the organs inside the belly,
particularly concerns physicians because increased levels have been
associated with insulin resistance, cardiovascular disease and other
metabolic syndromes. Visceral fat is located deeper in the body than
subcutaneous fat, which lies just under the skin.
study, the control group that did not exercise saw a sizable and
significant 8.6 percent increase in visceral fat in only six months,"
said Duke exercise physiologist Cris Slentz, Ph.D., lead author of a
study published in the October issue of the Journal of Applied
Physiology. "We also found that a modest exercise program equivalent to
a brisk 30-minute walk six times a week can prevent accumulation of
visceral fat, while even more exercise can actually reverse the amount
of visceral fat.
that these results shine a clear spotlight on the high costs Americans
are paying for their continued inactivity," Slentz continued. "I don't
believe that people in general have gotten lazier - it's more that they
are working too hard or are at their desks working on computers with
fewer opportunities for exercise. The situation is out of balance."
exercise program cited by Slentz is consistent with the latest
recommendations by the Centers for Disease Control and Prevention and
the American College of Sports Medicine. However, Slentz believes that
the public health message needs to be modified, especially for a
country where two out of three adults are overweight or obese.
"Until we are
able to prevent the weight many dieters regain following short-term
dieting success, we should place a greater national emphasis toward
prevention," Slentz said. "It will be a challenge to change the message
from 'exercise now to lose weight' to 'exercise now so in five years
you won't be 20 pounds heavier.'"
understand the effects of differing amounts of exercise, the
researchers studied 175 overweight sedentary men and women who were
beginning to show signs of lipid problems. They were randomized into
one of four groups: no exercise, low dose/moderate intensity
(equivalent of 12 miles of walking per week), low dose/vigorous
intensity (12 miles of jogging per week) or high dose/vigorous
intensity (20 miles of jogging per week).
trial was designed solely to better understand the role of exercise,
patients were told not to alter their diet during the course of the
trial, which lasted six months for the group that did not exercise or
eight-months for the exercise groups. The additional two months for the
exercise group came at the beginning of trial, when participants slowly
ramped up their exercise to their designated levels.
was carried out on treadmills, elliptical trainers or cycle ergometers
in a supervised setting. The researchers used computed tomography (CT)
both before the exercise program began and eight months later to
determine the extent and distribution of fat change.
no significant changes in visceral, subcutaneous or total fat in either
of the low exercise groups for men or women, which suggest that this
amount of exercise is adequate to prevent significant gain in fat
around the stomach, and that the amount of exercise is more important
than the intensity," Slentz said.
"On the other
hand, participants who exercised at a level equivalent to 17 miles of
jogging each week saw significant declines in visceral fat,
subcutaneous abdominal fat and total abdominal fat," Slentz continued.
"While this may seem like a lot of exercise, our previously sedentary
and overweight subjects were quite capable of doing this amount."
those participants exercising at the highest level saw a 6.9 percent
decrease in visceral fat and a 7 percent decrease in subcutaneous fat.
The Duke team
was led by cardiologist Dr. William Kraus, who received a $4.3 million
grant from the National Heart, Lung and Blood Institute in 1998 to
investigate the effects of exercise on sedentary overweight adults at
risk for developing heart disease and/or diabetes. The results of that
five-year trial, known as STRRIDE (Studies of Targeted Risk Reduction
Interventions through Defined Exercise), and other analyses of the data
collected, began to be published in 2002.
The Duke team
is currently enrolling patients in STRRIDE II, in which researchers are
seeking to determine the effects of weight training, alone and in
combination with aerobic training, on cardiovascular health.
Slentz and Kraus were Duke colleagues, Lori Aiken, Connie Bales, Ph.D.,
Johanna Johnson, and Brian Duscha. Joseph Houmard, Ph.D., and Charles
Tanner from East Carolina University, were also members of the team.
For more information on Duke University Medical Center, visit www.medschool.duke.edu.