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少脂肪的想法是有争议的，因为有氧运动经常在男性中导致脂肪减少，但在女性中效果较差。最近，我们证明了一种高强度间歇训练（HIIT）的高强度模型，即冲刺间歇训练（SIT； 4-6次重复“全力以赴”30秒的努力，中间间隔4分钟的活动休息）可以在男性和女性中减少脂肪。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，我们在三个实验阶段（无运动、静坐、中等强度有氧运动）中测量了运动后24小时的代谢。尽管运动量急剧减少（2分钟静坐运动vs 30分钟有氧运动），静坐诱导了运动后代谢的小幅但持续的增加，这可能有助于静坐诱导的脂肪减少。然而，这种运动后代谢的增加在性别上是相似的。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）和抑制食欲（PYY, GLP-1）激素的整合，这些激素对能量摄入有强烈的调节作用。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，性别差异可能与这些关键的性激素有关。此外，虽然研究表明运动可以改变能量摄入，但其机制尚不清楚。短期目标将探讨：1)月经周期中的性激素水平（雌激素、黄体酮）如何影响食欲调节激素；2)运动强度如何通过骨骼肌炎症标志物白介素-6 （IL-6）的增加改变食欲调节激素；3)血乳酸（肌肉代谢产物）。******这项拟议的工作将在人类身上进行，在几个小时内连续抽血（禁食、进食、运动前和运动后），以确定效果的时间过程。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，并为运动生理学、内分泌学和健康评估/运动处方方面的高素质人才提供培训。这项研究的长期影响将为食欲调节提供新的见解，以改善诱导体脂减少的策略，帮助治疗代谢紊乱，如肥胖和II型糖尿病。

***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.