TOPLINE: 

High-intensity exercise suppresses ghrelin levels more than moderate-intensity exercise, leading to a greater reduction in hunger. This effect may be more pronounced in women than in men.

METHODOLOGY:

• Ghrelin circulates in acylated and deacylated forms and is associated with hunger perceptions. Previous studies have indicated that acute exercise can modulate ghrelin levels, but data on the effect of exercise intensity on ghrelin levels and appetite remain limited.
• To close this gap, researchers examined 14 adults, including eight men (mean age, 43.1 years; body mass index [BMI], 22.2) and six women (mean age, 32.2 years; BMI, 22.7) who fasted overnight and then completed exercises of varying intensity.
• Participants completed a maximal graded cycle ergometer lactate threshold (LT) and peak oxygen consumption (VO2_peak) test to determine the exercise intensity.
• Three calorically matched cycle exercise bouts were conducted: Control (no exercise), moderate-intensity (power output at LT), and high-intensity (power output associated with 75% of the difference between LT and VO2_peak).
• Total ghrelin, acylated ghrelin, deacylated ghrelin, and lactate levels were measured at baseline and at multiple intervals post-exercise; appetite ratings were assessed using a visual analog scale at baseline and every 30 minutes thereafter.

TAKEAWAY:

• Total ghrelin levels were significantly lower during high-intensity exercise than during moderate-intensity and no exercise (P < .0001 for both).
• Both men and women had significantly lower deacylated ghrelin levels during high-intensity exercise than during moderate-intensity (P < .0001) and no exercise (P = .002), whereas only women had significantly lower acylated ghrelin levels during high-intensity exercise (P < .0001).
• Hunger scores were higher in the moderate-intensity exercise group than in the no exercise group (P < .01), with no differences found between high-intensity exercise and moderate-intensity or no exercise.
• Lactate levels were significantly higher during high-intensity exercise than during moderate-intensity and no exercise (P < .0001 for both).

IN PRACTICE:

“Exercise should be thought of as a ‘drug,’ where the ‘dose’ should be customized based on an individual’s personal goals,” the lead author said in a news release. “Our research suggests that high-intensity exercise may be important for appetite suppression, which can be particularly useful as part of a weight loss program.”

SOURCE:

This study was led by Kara C. Anderson, PhD, Department of Kinesiology, University of Virginia, Charlottesville, Virginia, and was published online on October 24, 2024, in the Journal of the Endocrine Society.

LIMITATIONS: 

The real-world application of the study was limited as participants were tested under fasting conditions, which may not have reflected typical exercise scenarios. The differences in fitness levels and exercise caloric expenditure between men and women may have affected the findings. The study only included lean individuals, limiting the applicability of the findings to individuals with overweight or obesity.

DISCLOSURES:

The study was supported by funds from the School of Education and Human Development, University of Virginia, and the National Institute of Diabetes and Digestive and Kidney Diseases. One author reported serving as an editor for the Journal of the Endocrine Society, which played no role in the evaluation of the manuscript.