Possible Role for Growth Hormone in Suppressing Acylated Ghrelin and Hunger Ratings During and After Intermittent Exercise of Different Intensities in Obese Individuals

Body weight is influenced by both food intake and energy expenditure. Acylated ghrelin enhances appetite, and its circulating level is suppressed by Growth Hormone. Data on the acylated ghrelin responses to exercise of different intensities in obese individuals are currently not available. This study examined the effects of an intermittent exercise protocol on acylated ghrelin levels and hunger ratings in obese people. Nine inactive male ran on the treadmill at 0900 with progressive intensities of 50, 60, 70, and 80% of VO2max for 10, 10, 5, and 2 min respectively. Blood samples were collected before the exercise at 0845 (-15 min as the resting values), after each workload (10, 23, 31, and 36 min during exercise), and at 30, 60, and 120 min thereafter. The control trial was conducted under identical conditions with the exception of exercise. Compared to the baseline, both acylated ghrelin levels and hunger ratings were suppressed at 70% of VO2max during exercise (17.74 vs. 9.80 pmol/L and 4.84 vs. 2.96 unit respectively) and remained significantly lower than the control trial 2 h after the cessation of exercise (13.95 vs. 20.32 pmol/L and 3.33 vs. 6.04 unit, respectively). Growth Hormone increased during the exercise period and peaked at 80% of VO2max. These findings indicate that acylated ghrelin concentrations and hunger ratings are suppressed during exercise and two hours thereafter in obese individuals, and it is possible that Growth Hormone caused the suppression of acylated ghrelin.