Body Composition & REE Responses to Bariatric Surgeries

描述（由申请人提供）： 严重肥胖者持续大量减肥后，身体成分和静息能量消耗（REE）的性质是一个重要的未解之谜。LABS人群非常适合研究这些问题，因为：他们的肥胖程度很少被研究，这使我们能够测试和扩展现有知识的适用范围;他们将经历大规模的体重减轻;体重减轻可能会持续很长一段时间，从而允许器官和组织质量的适应以及脂肪重新分布的发生;外科手术通过不同程度的限制和吸收不良来实现其效果，从而提供了一个机会来确定该尺寸是否以及如何影响身体组成和产热。超重和中度肥胖者在通常的负能量平衡条件下的体重减轻的组成通常是70-80%的脂肪和20-30%的瘦肉组织，然而，极肥胖者的体重减轻的组成可能不同。我们将使用先进的身体组成模型和测量方法分析体重发生快速和大幅度变化的LABS患者的体重组成。使用MRI，我们将描述在组织和器官水平和脂肪组织分布的身体成分的变化，使我们能够解决生物学和临床重要性的问题，包括身体成分的变化对REE的影响。具体目标是：1）确定接受不同类型减肥手术的人的体重变化的临床重要组成部分，关于脂肪量及其分布，以及关于无脂肪质量（FFM）;包括基线和手术后两个时间点的骨矿物质密度（BMD）、骨骼肌和特定器官，以及这些是否与手术类型相关; 2）测量手术诱导的体重减轻后REE的变化，并确定其与手术类型、身体组成区室的变化及其在随访期间的持续时间的关系。次要研究问题涉及心脏结构和功能的变化，心理功能，以及与大量减肥相关的激素（生长激素释放肽，瘦素，胰岛素）水平。来自哥伦比亚大学-威尔康奈尔大学和匹兹堡大学的符合条件的LABS患者将接受以下措施的某种组合：（脂肪和FFM），溴化钠示踪剂测定细胞外水，BodPod测定身体密度，全身MRI（脂肪组织及其分布;骨骼肌质量;肝脏、肾脏、心脏和大脑的质量）、双能X射线吸收测定法（髋部BMD、全身脂肪、FFM和骨矿物质含量）和REE。受试者将是非洲裔美国人和白人女性和男性（n=106; 50%（35>BMI kg/m2<45）将在手术前和手术后1年和2年接受MRI检查; 50%（45>BMI kg/m2<60）将仅在手术后进行MRI）在纽约和匹兹堡地点之间均等分布，并且在3种外科手术中均等分布：胃束带术;胆胰分流术和十二指肠转位术; Roux-en-Y胃旁路术。

DESCRIPTION (provided by applicant): Important unanswered questions surround the nature of body composition and resting energy expenditure (REE) after substantial and sustained weight loss by severely obese persons. The LABS population is well suited for the study of these questions in that: they are of a degree of fatness rarely studied, which allows us to test and extend the range of applicability of current knowledge; they will undergo massive weight loss; the weight loss is likely to be sustained over a long period of time thereby allowing for adaptations of organ and tissue mass and fat redistribution to occur; the surgical interventions achieve their effects by different degrees of restriction and malabsorption, providing an opportunity to determine whether and how this dimension affects body composition and thermogenesis. The composition of weight loss under usual negative energy balance conditions in overweight and moderately obese persons is typically 70-80% fat and 20-30% lean tissues, however it is likely that the composition of weight loss in extremely obese persons may be different. We will analyze the composition of body weight in LABS patients undergoing rapid and large changes in weight using advanced body composition models and measurement methods. Using MRI, we will describe body composition changes at the tissue and organ level and adipose tissue distribution allowing us to address questions of biological and clinical importance including the body composition changes influences on REE. The Specific Aims are to: 1) identify the clinically important components of weight change in persons undergoing different types of bariatric surgery on fat mass and its distribution, and on fat-free mass (FFM); including bone mineral density (BMD), skeletal muscle, and specific organs at baseline and two time-points post surgery, and whether these are related to the type of surgery; 2) measure the change in REE following surgery induced weight loss and determine its relation to type of surgery, to changes in body composition compartments, and its duration over the follow-up. Secondary research questions relate to changes in cardiac structure and function, psychological functioning, and hormonal (ghrelin, leptin, insulin) levels associated with massive weight loss. Consenting, eligible LABS patients from Columbia University-Weill Cornell and the University of Pittsburgh will undergo some combination of the following measures: total body water by deuterium dilution (fat and FFM), extracellular water by sodium bromide tracer, body density by the BodPod, whole-body MRI (adipose tissue and its distribution; skeletal muscle mass; mass of liver, kidneys, heart, and brain), dual energy-X-ray absorptiometry (hip BMD, total body fat, FFM, and bone mineral content), and REE. Subjects will be African-American and Caucasian women and men (n=106; 50 percent (35>BMI kg/m2<45) will undergo MRI studies before surgery and one and two years later; 50 percent (45>BMI kg/m2<60) will have MRI only post surgery) equally distributed between the New York and Pittsburgh sites, and equally distributed across 3 surgical procedures: gastric banding; biliary pancreatic diversion and duodenal switch; and Roux-en-Y gastric bypass.