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

描述（由申请人提供）：老年人是人口增长最快的部分之一，到2030年，65岁及以上的老年人预计将占美国人口的20%以上。与这种人口结构变化相对应的是，美国的肥胖人数正出现前所未有的增长。肥胖人数的增加也波及到老年人，预计到2010年将有超过37%的老年人肥胖。与年龄和肥胖相关的疾病风险的累积效应可能会给我们已经紧张的医疗保健系统带来巨大的问题。老年人患心脏代谢疾病（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。减少这些风险的一个潜在选择是促进老年人减肥。然而，这一建议在这一年龄组的益处证据有限，实际上可能对老年人有害——体重减轻会减少瘦肌肉量和骨密度，而老年人的体重指数越高，死亡率越低。了解如何在老年人中通过减肥饮食将风险降至最低的关键可能在于了解与年龄相关的身体成分变化，以及体重的过度增加，是如何影响心脏代谢风险因素和功能状态的。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，那么在骨骼肌和骨量与年龄相关的持续下降的情况下，减少总脂肪质量和瘦质量的减肥饮食是否不必要地增加了不良后果的风险？理想情况下，老年人使用规定的饮食干预与运动相结合，将能够优先减少内脏脂肪量，同时最大限度地减少瘦肌肉的损失，从而最大限度地改善心脏代谢和功能健康风险。我们建议对180名老年人进行随机对照试验，随访1年，以验证单独改变饮食组成或结合卡路里限制对老年人内脏脂肪储存（主要）有显著影响的假设，从而影响心脏代谢和功能健康风险因素和生活质量。与只运动的对照组相比，我们将评估体重维持和减肥（10%）干预对身体成分（具体目标#1：全身脂肪、内脏脂肪、皮下脂肪、肌肉量、细胞内脂质、骨密度）、心脏代谢危险因素(具体目标#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、白细胞介素-6)、功能状态和生活质量（具体目标#3：生活空间流动性、短体能电池、腿和手握力、短表单-36健康相关生活质量、体重对生活质量的影响）。公共卫生相关性：该项目的重要性，包括其与公共卫生的相关性，在于它将提供新的证据，证明单独改变饮食成分或与卡路里限制相结合，是否有益于心脏代谢疾病和功能障碍高风险的肥胖老年人，而不会造成伤害。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，旨在改善日益增长的长寿老年人的生活质量。

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.