Appetite regulation in humans: effect of sex hormones and exercise intensity

*运动可以在没有饮食干预的情况下减脂的想法是有争议的，因为单靠有氧运动经常会导致男性减脂，但对女性效果较差。最近，我们展示了一种高强度间歇训练的模式，称为短跑间歇训练(SIT；4-6次“全力以赴”30次S的努力，间隔4分钟的主动休息)导致男性和女性的脂肪减少。然而，男性的脂肪减少幅度更大。为了探索间歇训练诱导脂肪减少的机制，我们通过三个实验阶段(不锻炼、坐着、中等强度有氧运动)，在24小时内测量了运动后代谢。尽管运动量大幅减少(2分钟的运动SIT比30分钟的有氧运动)，SIT导致运动后代谢的小幅但持续的增加，这可能是SIT诱导的脂肪减少的原因。然而，这种运动后新陈代谢的增加在不同性别之间是相似的。这表明性激素和运动强度会影响食欲调节。*食欲调节涉及大脑中刺激食欲(Ghrelin)和食欲抑制(PYY，GLP-1)荷尔蒙的整合，这两种荷尔蒙敏锐地调节能量摄入。虽然已知进食和禁食会影响这些信号，但性激素和运动影响食欲调节的机制尚不清楚。因此，这项研究计划的长期目标是提高我们对人类食欲调节的具体机制的理解。众所周知，雌激素和黄体酮会影响能量摄入，性别差异很可能与这些关键的性激素有关。此外，尽管研究表明锻炼可以改变能量摄入，但其机制仍不清楚。短期目标将探索：1)月经周期中的性激素水平(雌激素、黄体酮)如何影响食欲调节荷尔蒙；2)由于骨骼肌炎症标志物白细胞介素6(IL-6)和3)血乳酸(肌肉代谢产物)的增加，运动强度如何改变食欲调节荷尔蒙。*这项拟议的工作将在人体上进行，通过几个小时的连续抽血(禁食、喂养、运动前和运动后)来确定影响的时间进程。将分析特定的食欲调节激素(grehlin，PYY，GLP-1)和潜在的生理介质(性激素，IL-6，乳酸)。这项研究将提高我们对食欲调节的理解，并为众多高素质的运动生理学、内分泌学和健身评估/运动处方方面的人员提供培训。这项研究的长期影响将为食欲调节提供新的见解，以改进诱导体脂减少的策略，帮助治疗肥胖症和II型糖尿病等代谢紊乱。

***The idea that exercise may produce fat loss without dietary intervention is controversial, as aerobic exercise alone frequently results in fat loss in males but is less effective in females. Recently, we demonstrated an intense model of high-intensity interval training (HIIT) known as sprint interval training (SIT; 4-6 repeated “all-out” 30 s efforts separated by 4 min active rest) induced fat loss in both males and females. However, the magnitude of the fat loss was greater in males. To explore the mechanism for the ability of interval training to induce fat loss, we measured post-exercise metabolism over 24 h across three experimental sessions (no exercise, SIT, moderate-intensity aerobic exercise). Despite the drastically reduced exercise volume (2 min of exercise SIT vs 30 min aerobic), SIT induced a small but prolonged increase in post-exercise metabolism, which likely contributes to the SIT-induced fat loss. However, this increase in post-exercise metabolism is similar across sex. This suggests sex hormones and exercise intensity affect appetite-regulation. ******Appetite regulation involves the integration of the appetite-stimulating (ghrelin) and appetite-inhibiting (PYY, GLP-1) hormones in the brain, which acutely regulate energy intake. While eating and fasting are known to influence these signals, the mechanisms by which sex hormones and exercise affect appetite-regulation are unknown. Thus, the long-term goal of this research program is to improve our understanding of the specific mechanisms responsible for human appetite regulation. As estrogen and progesterone are known to influence energy intake, sex differences likely involve these key sex hormones. Further, while research has demonstrated exercise alters energy intake, the mechanisms responsible remain unclear. The short-term objectives will explore how: 1) sex hormone levels (estrogen, progesterone) during the menstrual cycle affect appetite-regulating hormones; and 2) how the intensity of exercise alters the appetite-regulating hormones due to increases in the skeletal muscle inflammatory marker interleukin-6 (IL-6) and 3) blood lactate (product of muscle metabolism). ******The proposed work will be conducted in humans using serial blood draws (fasted, fed, pre- and post-exercise) over several hours to establish a time course of effects. Specific appetite-regulating hormones (grehlin, PYY, GLP-1) and potential physiological mediators (sex hormones, IL-6, lactate) will be analyzed. This research will improve our understanding of appetite regulation and provide training of numerous highly qualified personnel in exercise physiology, endocrinology, and fitness evaluation/exercise prescription. The long-term impact of this research will provide new insights on appetite regulation to improve strategies to induce body fat loss aiding the treatment of metabolic disorders such as obesity and type II diabetes.