EXERCISE AND A HIGH CARBOHYDRATE DIET: EFFECTS ON INSULIN ACTION

运动和高碳水化合物饮食：对胰岛素作用的影响

• 批准号: 7377670
• 负责人: W. DOUGLAS EVANS
• 金额: $ 0.47万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7377670
• 关键词: EXERCISE; CARBOHYDRATE; DIET; EFFECTS; INSULIN

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This protocol investigates the effects of a high complex carbohydrate (HiCHO) diet and exercise on body composition, insulin action, and muscle metabolism. Our hypothesis that a HiCHO diet would result in weight loss and improved insulin action is correct. In a group of older subjects with impaired glucose tolerance, we showed that subjects who consume a 60% CHO, 20% fat, 20% protein, 25 g fiber/1000 kcal diet ad libitum do not decrease energy intake but decrease body weight. These data indicate that negative fat balance may be achieved by decreasing fat intake with no change in total energy intake. While these data are provocative, they do not directly address the hypothesis that negative fat balance is obtained by decreasing fat intake. We propose to further test the hypothesis that negative fat balance may be obtained through decreased fat intake by changing the composition of dietary carbohydrate. The results of our previous study we seen in overweight subjects consuming a diet high in complex carbohydrate and fiber. Even though calculated energy intake was not reduced in subjects who lost weight, actual available energy may have been reduced due to the increase dietary fiber intake. We propose to use the same study design and provide overweight subjects with impaired glucose tolerance a diet that has the same macronutrient composition (60% CHO, 20% fat, and 20% protein) but substitute simple carbohydrates with a higher glycemic index for complex carbohydrate. We will quantify fat balance by measuring both hepatic and adipocyte de novo lipogenesis and the rate of lipid oxidation. In this way we will determine the extent to which high glycemic index CHO results in increase lipid synthesis or, as we hypothesis, the capacity for de novo lipogenesis is very limited, even after adaptation to a high CHO diet. We will also examine the response to a change in lipid intake. There has been much speculation that a diet that is rich in mono and polyunsaturated fats contributes to improved insulin action and a more favorable body weight. We will feed subjects an ad libitum diet rich in poly and mono unsaturated fat (40% fat, 40% CHO, and 20% protein as well as a diet with the same macronutrient content but high in saturated fat (very similar to habitual dietary intake in Central Arkansas). In addition to rates of lipogenesis, we will also examine energy and substrate balance (intake vs oxidation) in our room calorimeter. Insulin stimulated glucose disposal will be examined before and after the dietary interventions. These prospective, randomized, controlled trials will address the important issue of the metabolic consequences of changing macronutrient intake in subjects at great risk for the development of type 2 diabetes.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。该方案研究了高复合碳水化合物（HiCHO）饮食和运动对身体成分、胰岛素作用和肌肉代谢的影响。我们的假设是，HiCHO饮食将导致体重减轻和改善胰岛素作用是正确的。在一组葡萄糖耐量受损的老年受试者中，我们发现，随意摄入60% CHO、20%脂肪、20%蛋白质、25 g纤维/1000 kcal饮食的受试者不会减少能量摄入，但会减轻体重。这些数据表明，可以通过减少脂肪摄入而不改变总能量摄入来实现负脂肪平衡。虽然这些数据是挑衅性的，但它们并没有直接解决通过减少脂肪摄入获得负脂肪平衡的假设。我们建议进一步验证这一假设，即通过改变膳食碳水化合物的组成来减少脂肪摄入，可以获得负脂肪平衡。我们之前的研究结果显示，超重的受试者饮食中含有大量的复合碳水化合物和纤维。即使计算的能量摄入量在体重减轻的受试者中没有减少，但由于膳食纤维摄入量的增加，实际可用能量可能已经减少。我们建议使用相同的研究设计，并为糖耐量受损的超重受试者提供具有相同常量营养素组成（60% CHO，20%脂肪和20%蛋白质）的饮食，但用更高血糖指数的简单碳水化合物替代复合碳水化合物。我们将通过测量肝脏和脂肪细胞从头脂肪生成和脂质氧化速率来量化脂肪平衡。通过这种方式，我们将确定高血糖指数CHO导致脂质合成增加的程度，或者正如我们假设的那样，即使在适应高CHO饮食后，从头脂肪生成的能力也非常有限。我们还将研究对脂质摄入量变化的反应。有很多推测认为，富含单不饱和脂肪和多不饱和脂肪的饮食有助于改善胰岛素作用和更有利的体重。我们将向受试者提供富含多不饱和脂肪和单不饱和脂肪（40%脂肪、40% CHO和20%蛋白质）的自由采食饲料以及常量营养素含量相同但饱和脂肪含量高的饲料（与阿肯色州中部的习惯性饮食摄入量非常相似）。除了脂肪生成率，我们还将在我们的房间热量计中检查能量和底物平衡（摄入与氧化）。将在饮食干预前后检查胰岛素刺激的葡萄糖处置。这些前瞻性、随机、对照试验将解决改变大量营养素摄入量对2型糖尿病发展风险很大的受试者的代谢后果这一重要问题。