Role of Exercise in the Endocrine Control of Feeding

描述（由申请人提供）： 数以百万计的肥胖美国人未能实现并保持大量的脂肪损失，但少数人通过将大量运动与饮食控制相结合而成功地做到了这一点。虽然已经详细研究了久坐条件下进食的激素和生理控制，但对运动期间代谢燃料的消耗如何影响这些控制知之甚少。更好地了解代谢能量消耗是否在意识水平上无法检测到，以及运动强度在多大程度上可能通过激素机制抑制食欲，可能会导致肥胖个体减肥的改进策略。根据我们的初步研究和其他人的结果，我们假设：（1）运动能量消耗引起的循环代谢燃料浓度的变化不会被有意识地检测为饥饿和进食欲望水平的变化，或者通过食物消耗量的变化进行补偿，与一天中从膳食中扣除卡路里时的适当心理物理和生理调整相反;（2）代谢能量消耗的变化通过调节循环代谢燃料可用性的自主和激素反射来计量和补偿;和（3）在高运动强度下，对运动的激素和/或交感神经反应可另外诱导对饥饿的主动抑制。我们的第一个具体目标是比较在没有或有静脉营养补充的情况下，通过运动或通过禁食引起的同等能量不足如何影响（1）饥饿感、进食欲望和餐前进食能力的估计，以及餐后的饱腹感;（2）一方面分泌反调节激素ghrelin、生长激素（GH）、肾上腺素（E）和胰高血糖素，另一方面分泌餐后激素胆囊收缩素=CCK、胰高血糖素样肽-1（GLP-1）、肽YY ;胰岛素和瘦素，以及（3）代谢燃料葡萄糖和游离脂肪酸（FFA）的血浆浓度。我们的第二个具体目标是比较心理-生理（如1），激素（如2）和代谢（如3）对两种强度的运动的反应，在35%和70%的最大努力。这些研究的结果将扩展对能量调节的理论理解，并为肥胖个体的减肥策略提供见解。

DESCRIPTION (provided by applicant): Millions of obese Americans fail to achieve and maintain substantial fat losses, but a small number are successful in doing so by combining large volumes of exercise with dietary control. Although the hormonal and physiological controls of feeding under sedentary conditions have been studied in great detail, how expenditure of metabolic fuels during exercise affects these controls is poorly understood. A better understanding of whether the metabolic energy expenditure is undetectable at the conscious level, and to what extent exercise intensity may suppress appetite through hormonal mechanisms, could lead to improved strategies for fat loss in obese individuals. Based on our preliminary study and the results of others, we hypothesize that (1) changes in the concentration of circulating metabolic fuels caused by energy cost of exercise are not detected consciously as changes in the levels of hunger and desire to eat, or compensated for through changes in the quantities of food consumed, in contrast to the appropriate psychophysical and physiological adjustments when calories are withheld from meals during a day; (2) changes in the metabolic energy expenditure are metered and compensated for by autonomic and hormonal reflexes which adjust circulating metabolic fuel availability; and (3) at high exercise intensities, hormonal and/or sympathetic responses to exercise may additionally induce an active suppression of hunger. Our first specific aim is to compare how an equal energy deficit incurred through exercise or through withholding of food, either in the absence, or in the presence of intravenous nutrient replacement, affects (1) sensations of hunger, desire to eat, and estimate of capacity to eat before the meal, and sensation of fullness after the meal; (2) secretion of counter-regulatory hormones ghrelin, growth hormone (GH), epinephrine (E), and glucagon on one hand and of postprandial hormones cholecystokinin=CCK, glucagon-like peptide-1 (GLP-1), peptide YY ; insulin, and leptin, and (3) plasma concentrations of metabolic fuels glucose and free fatty acids (FFA). Our second specific aim is to compare the psycho-physical (as in 1), hormonal (as in 2), and metabolic (as in 3) responses to exercise of two intensities, at 35% and 70% of maximal effort. The findings from these studies will extend theoretical understanding of energy regulation and provide insight for improved weight-loss strategies in obese individuals.