In a new study, researchers have shown that vigorous exercise can suppress a person's hunger by affecting the release of two key appetite hormones, ghrelin and peptide YY.
According to the study, 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.
Overall, the study shows that aerobic exercise is better at suppressing appetite than non-aerobic exercise and provides a possible explanation for how that happens.
Senior author, David J. Stensel of Loughborough University in the United Kingdom said that the findings of the study might eventually lead to more effective ways to use exercise to help control weight.
Ghrelin is the only hormone known to stimulate appetite was originally identified for its role as a growth hormone. On the other hand Peptide YY suppresses appetite.
In the study, 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.
It was 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.
On the basis of the hunger ratings the participants filled out, both aerobic and resistance exercise suppressed hunger, but aerobic exercise produced a greater suppression of hunger.
Stensel said that the observed changes were short term for both types of exercise, lasting about two hours, including the time spent exercising.
"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. The findings suggest a similar, although slightly attenuated response, for weight lifting exercise," said Stensel.
The researchers said that previous studies have been inconclusive about whether exercise decreases ghrelin levels, but this study may help explain those mixed results.
While the study showed that exercise suppresses appetite hormones, the next step is to establish whether this change actually causes the suppression of eating.
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.