Calorie Restriction & Body Composition, Function, & QoL in Older Adults

描述(申请人提供)：老年人是人口增长最快的部分之一，到2030年，65岁及以上的人预计将占美国人口的20%以上。在这种人口结构变化的同时，美国的肥胖者数量正在经历前所未有的增长。肥胖症的增加也延伸到年龄较大的人，预计到2010年，超过37%的老年人将肥胖。与年龄和肥胖相关的疾病风险的累积影响可能会给我们本已紧张的医疗保健系统带来巨大的问题。老年人患心脏代谢性疾病(如糖尿病、心脏病)以及功能状态和生活质量下降的风险将非常高。降低这些风险的一个潜在选择是促进老年人减肥。然而，这一建议的证据有限，支持其在这个年龄段的好处，实际上可能对老年人有害--减肥可以减少精瘦肌肉质量和骨密度，而较高的身体质量指数与较低的老年人死亡率相关。了解如何通过老年人减肥饮食将风险降至最低的关键可能是了解与年龄相关的身体成分变化，除了过度体重增加外，如何影响心脏代谢风险因素和功能状态。先前的研究表明，内脏脂肪组织可能是导致老年人肥胖相关风险的主要原因，导致心脏代谢性疾病风险增加和功能状态恶化。如果内脏脂肪是增加肥胖老年人风险的关键因素，那么减少总脂肪质量和瘦质量的减肥饮食是否会不必要地增加与年龄相关的骨骼肌和骨量持续下降的不良后果的风险？理想情况下，使用处方饮食干预结合运动的老年人将能够优先减少内脏脂肪质量，同时最大限度地减少精瘦肌肉的损失，以获得心脏代谢和功能性健康风险的最大改善。我们建议在180名老年人中进行一项随机对照试验，随访1年，以检验以下假设：饮食结构的改变单独或与卡路里限制一起对老年人的内脏脂肪储存有显著影响，从而对心脏代谢和功能性健康风险因素和生活质量产生影响。与单纯锻炼的对照组相比，我们将评估维持体重和减肥(10%)干预措施对身体成分(特定目标#1：全身脂肪、内脏脂肪、皮下脂肪、肌肉质量、肌细胞内脂肪、骨密度)、心脏代谢危险因素(特定目标#2：血压、血糖、胰岛素、血脂、C反应蛋白、脂联素、瘦素、肿瘤坏死因子-1、白介素6)、功能状态和生活质量(特定目标#3：生活空间活动能力、短体能电池、腿部和手握力、与健康相关的生活质量简表36)、功能状态和生活质量的影响。体重对生活质量的影响(Lite)。公共卫生相关性：该项目的意义，包括其与公共健康的相关性，是它将提供新的证据，表明改变饮食结构是否有利于在不造成伤害的情况下，对患有心脏代谢性疾病和功能障碍的高风险肥胖老年人有益。这项研究产生的重要结果可用于为临床决策和社区公共卫生倡议提供信息，旨在改善越来越多的老年人的生活质量，这些老年人寿命更长。

DESCRIPTION (provided by applicant): Older adults represent one of the fastest growing segments of the population, and by 2030, those aged 65 and older are expected to make up more than 20% of the US population. Parallel to this demographic shift, the US is experiencing an unprecedented increase in the number of people who are obese. This increase in obesity extends to those who are older as well, with over 37% of older adults expected to be obese by 2010. The cumulative effects of age- and obesity-related disease risk could create a tremendous problem for our already strained health care system. The risks of cardiometabolic diseases (e.g., diabetes, heart disease) and declines in functional status and quality of life for older adults will be extraordinarily high. One potential option to reduce these risks is to promote weight loss in older adults. However, this recommendation has limited evidence to support its benefit in this age group and may actually be harmful for older adults-weight loss can decrease lean muscle mass and bone mineral density, and higher body mass index has been associated with lower mortality in older adults. The key to understanding how to minimize risk with weight reducing diets in older adults may be in understanding how age-related changes in body composition, in addition to excess weight gain, affect cardiometabolic risk factors and functional status. Prior research suggests that visceral adipose tissue may be primarily responsible for driving obesity associated risk in older adults, leading to increased cardiometabolic disease risk and worsened functional status. If visceral fat is a key factor that increases risk in obese older adults, do weight reducing diets that decrease total fat mass as well as lean mass unnecessarily increase risk of an adverse outcome in the setting of ongoing age-related declines in skeletal muscle and bone mass? Ideally, older adults using a prescribed dietary intervention combined with exercise would be able to preferentially reduce visceral fat mass, while minimizing loss of lean muscle, to obtain maximum improvements in both cardiometabolic and functional health risk. We propose to conduct a randomized, controlled trial in 180 older adults with 1 year follow up to test the hypothesis that changes in diet composition alone or in combination with calorie restriction have a significant effect on visceral fat stores (primarily) in older adults and as a result have an impact on cardiometabolic and functional health risk factors and quality of life. Compared to an exercise only control group, we will assess the effects of weight maintenance and weight loss (10%) interventions on body composition (Specific Aim #1: total body fat, visceral fat, subcutaneous fat, muscle mass, intramyocellular lipid, bone density), cardiometabolic risk factors (Specific Aim #2: blood pressure, blood glucose, insulin, lipids, C-reactive protein, adiponectin, leptin, tumor necrosis factor-1, interleukin-6), functional status, and quality of life (Specific Aim #3: life space mobility, Short Physical Performance Battery, leg and hand grip strength, Short Form-36 Health Related Quality of Life, Impact of Weight on Quality of Life-Lite). PUBLIC HEALTH RELEVANCE: The significance of this project, including its relevance for public health, is the new evidence it will provide regarding whether changes in diet composition alone or in combination with calorie restriction benefits, without causing harm, obese older adults at high risk for cardiometabolic disease and functional impairment. Important results generated from this study can be used to inform both clinical decision-making and community-based public health initiatives designed to improve the quality of life of the increasing population of older adults who are living longer.