FOR IMMEDIATE RELEASE
December 11, 2008
Contact: Christine Guilfoy
Office: (301) 634-7253
cguilfoy@the-aps.org
Exercise Suppresses
Appetite By Affecting Appetite Hormones
BETHESDA, Md. (Dec. 11, 2008)
− A vigorous 60-minute workout on a treadmill affects the release
of two key appetite hormones, ghrelin and peptide YY, while 90 minutes of
weight lifting affects the level of only ghrelin, according to a new study.
Taken together, the research shows that aerobic exercise is better at
suppressing appetite than non-aerobic exercise and provides a possible
explanation for how that happens.
This line of research may eventually lead to more
effective ways to use exercise to help control weight, according to the
senior author, David J. Stensel of Loughborough University in the United
Kingdom.
The study, “The influence of resistance and aerobic
exercise on hunger, circulating levels of acylated ghrelin and peptide YY in
healthy males,” appears in the online edition of The American Journal of
Physiology-Regulatory, Integrative and Comparative Physiology, published
by The American Physiological Society. The authors are David R.
Broom, James A. King and David J. Stensel of Loughborough University, and
Rachel L. Batterham of University College, London.
Treadmill versus weight lifting
There are several hormones that help regulate appetite,
but the researchers looked at two of the major ones, ghrelin and peptide YY.
Ghrelin is the only hormone known to stimulate appetite. Peptide YY
suppresses appetite.
Ghrelin was discovered by researchers in Japan only
about 10 years ago and was originally identified for its role as a growth
hormone. Only later did its role in stimulating appetite become known.
Peptide YY was discovered less than 25 years ago.
In this experiment, 11 male university students did
three eight-hour sessions. During one session they ran for 60 minutes on a
treadmill, and then rested for seven hours. During another session they did
90 minutes of weight lifting, and then rested for six hours and 30 minutes.
During another session, the participants did not exercise at all.
During each of the sessions, the participants filled
out surveys in which they rated how hungry they felt at various points. They
also received two meals during each session. The researchers measured
ghrelin and peptide YY levels at multiple points along the way.
They found that the treadmill (aerobic) session caused
ghrelin levels to drop and peptide YY levels to increase, indicating the
hormones were suppressing appetite. However, a weight-lifting (non-aerobic)
session produced a mixed result. Ghrelin levels dropped, indicating appetite
suppression, but peptide YY levels did not change significantly.
Based on the hunger ratings the participants filled
out, both aerobic and resistance exercise suppressed hunger, but aerobic
exercise produced a greater suppression of hunger. The changes the
researchers observed were short term for both types of exercise, lasting
about two hours, including the time spent exercising, Stensel reported.
“The finding that hunger is suppressed during and
immediately after vigorous treadmill running is consistent with previous
studies indicating that strenuous aerobic exercise transiently suppresses
appetite,” Stensel said. “The findings suggest a similar, although slightly
attenuated response, for weight lifting exercise.”
Focus on active ghrelin
Previous studies have been inconclusive about whether
exercise decreases ghrelin levels, but this study may help explain those
mixed results, according to the researchers.
Ghrelin comes in two forms, acylated and non-acylated.
The researchers measured acylated ghrelin, also called active ghrelin,
because it can cross the blood-brain barrier and reach the appetite center
in the brain. Stensel suggests that future research concentrate on active
ghrelin.
While the study showed that exercise suppresses
appetite hormones, the next step is to establish whether this change
actually causes the suppression of eating.
NOTE TO EDITORS: To interview Dr. Stensel,
please contact Christine Guilfoy at (301) 634-7253 or at
cguilfoy@the-aps.org. To listen to an interview with Dr. Stensel, go to
www.lifelines.tv and click on Episode 16.
Funding: School of Sport and Exercise Sciences,
Loughborough University.
***
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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