FOR IMMEDIATE RELEASE
September 17, 2008
Contact: Christine Guilfoy
Office: (301) 634-7253
cguilfoy@the-aps.org
Older People Who Diet Without Exercising
Lose Valuable Muscle Mass
Exercise improves fitness, reduces fat
BETHESDA, Md. (Sept. 17, 2008) − A group
of sedentary and overweight older people placed on a four-month exercise
program not only became more fit, but burned off more fat, compared to older
sedentary people who were placed on a diet but did not exercise.
The new study also showed that when older people diet
without exercising, they lose more lean muscle compared to those who
exercise, said senior researcher Bret H. Goodpaster. When they combined
weight loss with exercise, it nearly completely prevented the loss of lean
muscle mass. The results are important because older people tend to lose
muscle mass as they age and too much muscle loss may interfere with
activities of daily living.
The study, “Separate and combined effects of exercise
training and weight loss on exercise efficiency and substrate oxidation,”
appears in the current issue of the Journal of Applied Physiology,
published by The American Physiological Society. Francesca Amati,
John J. Dube, Chris Shay and Goodpaster, all of the University of
Pittsburgh, carried out the study.
Study looks at exercise
efficiency
The researchers wanted to know the best way to get
better (more efficient) at completing a defined exercise task. In
particular, they wanted to know if greater fitness could be achieved through
exercise training, weight loss (through dieting), or both. In addition, they
wanted to know which fuel source the body would draw upon, carbohydrates or
fats, under these different conditions.
The 64 participants were 60-75 years of age and were
either overweight or obese. All of the participants were sedentary at the
outset of the study. The researchers divided the participants into three
groups:
-
exercise only
-
diet only
-
exercise plus diet
Those who exercised could either walk on a treadmill or
ride a stationary bicycle, although most chose to walk. The dieters reduced
their caloric intake to achieve a 10% weight loss by the end of the
four-month study period. The final group combined both the daily exercise
and the diet.
Exercise increases
efficiency, burns more fat
The researchers measured how many calories the
participants expended during a set work load on a stationary bicycle at the
beginning and at the end of the experiment. They found that the:
-
Exercise group expended fewer calories (became more
efficient) on the exercise task at the end of the study compared to the
beginning.
-
Exercise group drew more on fat stores as the source of
their body’s fuel.
-
Diet-only group did not gain efficiency in performing the
exercise task, even though they weighed less at the end of the
experiment.
-
Diet-only group’s weight loss resulted from a loss of both
muscle and fat.
-
Exercise plus diet group was the most efficient at the
exercise task at the end of the experiment. This shows an additive
effect of both dieting and exercise, but most of that benefit was due to
exercise.
-
Exercise plus diet group, like the exercise-only group,
drew more on fat stores as an energy source.
“The take-home message is that, even among older people
and during a fairly short period of time, exercise produces metabolic
changes that require the expenditure of fewer calories during physical
activity,” Goodpaster said. Exercise also allowed older people to more
preferentially burn fat, which may be healthier metabolically.”
NOTE TO EDITORS: To interview Dr. Goodpaster,
please contact Christine Guilfoy at (301) 634-7253 or at
cguilfoy@the-aps.org.
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (www.The-APS.org/press)
has been an integral part of this discovery process since it was established
in 1887.
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