Long-Term Effects of Weight Loss and Supplemental Protein on Physical Function

项目总结/摘要 肥胖加剧了与年龄相关的身体功能下降，是行动能力残疾的一个强有力的决定因素。 鉴于三分之一的老年人肥胖，确定有效的治疗方法，防止肥胖相关的 身体机能的下降是迫切需要的。随着年龄的增长，瘦体重的减少有助于与年龄有关的 身体机能的下降和目前的减肥建议可能会进一步加剧这种瘦的损失 马萨诸塞州虽然减肥改善身体功能，而在体重减轻的状态，大多数人是 不能长期维持减肥效果。此外，中年和老年人的数据 表明体重减轻后的体重恢复是由相对于瘦体重更大的脂肪组成的。 因此，体重减轻和随后的体重恢复可能导致甚至更少的相对瘦体重和更差的 物理功能。在减肥过程中消耗的蛋白质量可能是保持体重的关键决定因素。 减肥期间的瘦体重和减肥后更高的蛋白质摄入量可能会促进减肥 通过减少总体体重恢复来维持，部分地通过有利于恢复瘦体重而不是脂肪来维持。然而，在这方面， 是否潜在的好处瘦质量保留和增长与高蛋白饮食期间和 在肥胖的老年人中，体重减轻后转化为身体功能的更大改善， 未知我们的主要目标是确定高蛋白质（1.2 g/kg体重/d）/低碳水化合物 (CHO)肥胖老年人6个月减肥干预期间的饮食改善了身体功能 与等热量低蛋白质（当前RDA为0.8 g/kg体重/d）/高CHO饮食相比， 在12个月的随访期间继续高蛋白/低CHO饮食可以更好地维持 改善身体功能。我们计划在225名肥胖（BMI 30-40）患者中进行一项为期18个月的随机试验 kg/m2）、老年（65-79岁）男性和女性（SPPB ≤10），以确定较高的 在6个月的减肥干预期间进行蛋白质/低CHO饮食，随后进行12个月的随访， 1)身体功能（通过扩展的短期身体表现组合（expSPPB）评估），肌肉 力量和功率），和2）体重维持和身体组成（通过DXA和CT评估）。我们将 还评估了高蛋白/低CHO饮食对骨矿物质密度变化的影响， 心脏代谢危险因素。所有参与者将接受为期6个月的减肥干预， 随访6个月，随机分为3组：1）6个月低蛋白/高CHO饮食 体重减轻和12个月随访期; 2）6个月体重减轻的高蛋白/低CHO饮食 3）6个月体重减轻期和12个月随访期的高蛋白/低CHO饮食。 确定在减肥期间和减肥后是否高蛋白饮食能最大限度地提高潜在的益处 对身体功能的影响同时最小化体重减轻的潜在不利影响（例如，瘦骨丢失 质量）可能会导致更有效的减肥干预肥胖的老年人。

Project Summary/Abstract Obesity exacerbates age-related declines in physical function and is a strong determinant of mobility disability. Given that one-third of older adults are obese, identifying effective therapies that prevent obesity-related declines in physical function are urgently needed. The loss of lean mass with age contributes to age-related declines in physical function and current weight loss recommendations may further exacerbate this loss of lean mass. Although weight loss improves physical function while in the weight-reduced state, most individuals are not successful at long-term maintenance of weight loss. Furthermore, data from middle aged and older adults suggest that weight regain following weight loss is comprised of greater fat relative to lean mass. Consequently, weight loss and subsequent weight regain may lead to even less relative lean mass and worse physical function. The amount of protein consumed during weight loss may be a key determinant in preserving lean mass during weight loss and higher protein intake following weight loss may enhance weight loss maintenance by reducing overall weight regain, in part, by favoring regain of lean mass over fat. However, whether the potential benefit of lean mass retention and accretion with a higher protein diet during and subsequent to weight loss translates into greater improvements in physical function in obese older adults is unknown. Our primary goal is to determine whether a higher protein (1.2 g/kg body wt/d) / lower carbohydrate (CHO) diet during a 6-month weight loss intervention in obese older adults improves physical function compared with an isocaloric lower protein (current RDA of 0.8 g/kg body wt/d) / higher CHO diet and whether continuing a higher protein / lower CHO diet during the 12-month follow-up results in better maintenance of improved physical function. We propose to conduct an 18-month randomized trial in 225 obese (BMI 30-40 kg/m2), older (65-79 yrs) men and women at risk for disability (SPPB ≤10) to determine the effects of a higher protein / lower CHO diet during a 6-month weight loss intervention followed by 12 months of follow-up on 1) physical function (assessed by the expanded Short Physical Performance Battery (expSPPB), muscle strength and power), and 2) weight maintenance and body composition (assessed by DXA and CT). We will also assess the effects of a higher protein / lower CHO diet on changes in bone mineral density and cardiometabolic risk factors. All participants will undergo a 6-month weight loss intervention followed by 12 months of follow-up with randomization to one of 3 groups: 1) lower protein / higher CHO diet for the 6-month weight loss and 12-month follow-up phases; 2) higher protein / lower CHO diet for the 6-month weight loss phase only; or 3) higher protein / lower CHO diet for the 6-month weight loss and 12-months follow-up phases. Determining whether a higher protein diet during and subsequent to weight loss maximizes potential benefits on physical function while minimizing potential adverse effects of weight loss (e.g., loss of lean and bone mass) may lead to more effective weight loss interventions for obese older adults.