The Impact of Exercise Intensity and Sex on Endogenous Ghrelin Levels and Appetite in Healthy Humans

Context: Ghrelin circulates in acylated (AG) and deacylated (DAG) forms, which are known to affect appetite. Although acute exercise has been shown to modulate ghrelin levels, data on the impact of exercise intensity on AG and DAG levels and their effects on appetite are sparse and primarily limited to males.

Objective: To investigate the effect of exercise intensity and sex on ghrelin levels and appetite in untrained humans.

Methods: Eight males (age: 43.1 ± 10.9 years; body mass index [BMI]: 22.2 ± 1.7 kg/m²; peak oxygen consumption [VO_2peak]: 36.3 ± 6.4 mL/kg/min) and 6 females (age: 32.2 ± 11.1 years; BMI: 22.7 ± 1.0 kg/m²; VO_2peak: 29.2 ± 4.0 mL/kg/min) completed a maximal graded cycle ergometer lactate threshold (LT)/VO_2peak test. These data were used to determine the exercise intensity on 3 subsequent randomized control or calorically matched cycle exercise bouts: (1) CON, no exercise; (2) MOD, the power output at LT; (3) HIGH, the power output associated with 75% of the difference between LT and VO_2peak. Perception of appetite was analyzed using visual analog scales.

Results: Females had higher levels of total ghrelin (TG) (P = .03) and DAG (P = .01) at baseline than males. Both groups exhibited reduced DAG levels in HIGH compared with MOD and CON (P < .0001-.004); however, only females had significantly reduced AG in HIGH (P < .0001). Hunger scores were higher in MOD than in CON (P < .01).

Conclusion: High-intensity may be superior to moderate-intensity exercise for reducing ghrelin levels and modifying hunger, and sex may impact this response.