Ethnic Influences on Stress, Energy Balance and Obesity in Adolescents

肥胖是美国最严重的公共卫生问题之一， 过去三十年来，它与一系列短期和长期的医疗和心理社会问题有关。 青春期是肥胖发展和持续的关键时期，与变化相关联 饮食、体育活动和健身、脂肪分布和胰岛素敏感性。有种族和性别特异性 肥胖症的患病率和负担的差异。非洲裔美国人（AA）女性的发病率最高， 肥胖，冠心病和代谢综合征的聚集危险因素是AA的两倍 男性。肥胖患病率和负担的种族和性别差异的原因还不清楚 明白AA经历更高的压力水平比非西班牙裔白人（NHW）由于经济和社会 压力对高能量饮食和肥胖的影响在女性中更为突出。更好的 了解将压力与肥胖联系起来的机制，特别是在青春期， 肥胖、压力体验增加以及对压力的更强的行为和生理反应出现， 将有助于减少AA女性肥胖和相关医疗条件的新临床指南。 生理应激系统影响肥胖并通过下丘脑介导其适应功能。 垂体-肾上腺轴（HPA轴）。长时间的应激诱导的糖皮质激素分泌会促进 能量密集饮食（EI）和腹部脂肪沉积直接和间接通过其对代谢的影响 荷尔蒙压力也会减少身体活动，改变能量平衡。拟议的研究将审查 应激和HPA轴对100名AA和100名AA大鼠EI和体力活动相关能量消耗的影响 NHW青少年女性。将在两种情况下评估对EI的影响，自然环境和 在包含标准化心理社会压力源的受控条件下。压力将在 自然环境作为多个域（即，个人、家庭和社会），以及自置居所津贴的若干指数 将获得代表昼夜变化、其在12-15周内的状态和对应激的反应性的轴。肥胖症- 将通过人体测量、脂肪分布和心脏代谢生物标志物测量相关参数。 压力、HPA活性/功能、能量平衡和肥胖相关参数之间的关联将被 在AA和NHW样本之间和内部进行比较。结合起来，它们将提高我们对 肥胖的种族和个体差异的社会因素和生物行为机制，并促进 根据个体化原则，在种族群体内和跨种族群体开发有效的治疗方法， 药据我们所知，客观测量的饮食摄入量和能量消耗的种族差异， 对压力的反应或其潜在的生理机制尚未在青少年中进行评估， 成年人了这是一个重要的知识差距，在我们的努力，以发展更好的循证转化肥胖 预防和体重控制干预措施，因为传统干预措施对少数群体青年无效。

Obesity is one of the most serious public health problems in the US; its prevalence has tripled in the last three decades and is associated with a range of short- and long-term medical and psychosocial problems. Adolescence is a critical period for the development and persistence of obesity, and is associated with changes in diet, physical activity and fitness, fat distribution and insulin sensitivity. There are racial and sex-specific disparities in the prevalence and burden of obesity. African-American (AA) females have the highest rates of obesity, and the clustered risk factors for coronary heart disease and metabolic syndrome are twice that of AA males. The reasons for racial and sex-specific disparities in the prevalence and burden of obesity are not well understood. AA experience higher stress levels than Non-Hispanic Whites (NHW) due to economic and social inequalities, and the effect of stress on energy-dense diet and adiposity is more prominent in females. A better understanding of the mechanisms that link stress to obesity, particularly during adolescence when high rates of obesity, increased stressful experiences and stronger behavioral and physiological responses to stress emerge, will contribute to new clinical guidelines for reducing obesity and associated medical conditions in AA females. The Physiological stress system affects obesity and mediates its adaptive functions via hypothalamic- pituitary-adrenal (HPA) axis. Prolonged stress-induced glucocorticoid secretion promotes the consumption of energy-dense diet (EI) and abdominal fat deposition both directly and indirectly through its effects on metabolic hormones. Stress also reduces physical activity and alters energy balance. The proposed study will examine the effects of stress and HPA axis on EI and physical activity-related energy expenditure in 100 AA and 100 NHW adolescent females. The effects on EI will be assessed in two contexts, the natural environment and under controlled conditions incorporating a standardized psychosocial stressor. Stress will be assessed in the natural environment as multiple domains (i.e., individual, family and social), and several indices of the HPA axis will be obtained to represent diurnal variation, its status over 12-15 weeks and reactivity to stress. Obesity- related parameters will be measured through anthropometry, fat distribution and cardio-metabolic biomarkers. Associations among stress, HPA activity/function, energy balance and obesity-related parameters will be compared between and within AA and NHW samples. In combination they will improve our understanding of the social factors and biobehavioral mechanisms of both racial and individual differences in obesity and facilitate the development of effective treatments within and across racial groups according to the principles of individualized medicine. To our knowledge, racial differences in objectively-measured diet intake and energy expenditure in response to stress, or their underlying physiological mechanisms, have not been assessed in adolescents or adults. This is an important knowledge gap in our efforts to develop better evidence-based translational obesity prevention and weight-control interventions as the traditional interventions are not effective with minority youth.