DIETARY COMPOSITION, OBESITY, AND CARDIOVASCULAR RISK

冠心病（CHD）是导致死亡和残疾的主要原因。 肥胖通过对葡萄糖、脂蛋白和血压产生不利影响而增加CHD风险。目前的共识是，饮食中饱和脂肪和胆固醇（C）的限制有利于降低低密度脂蛋白（LDL）和降低冠心病的风险，但有争议的其他方面的饮食。 我们建议检查三种符合国家胆固醇教育计划第二步饮食标准的饮食对体重和成分以及冠心病危险因素的影响（LDL C、HDL C、残余脂蛋白C、Lp（a）C、胰岛素、糖化血红蛋白、葡萄糖、和血压）在空腹和非空腹状态下（饭后4小时）80名男性和女性（男性，50岁以上，65岁以下，绝经后且小于65岁的女性），LDL C值大于或等于130 mg/dl，且体重指数大于或等于28且小于38 kg/m2。 将进行一项四阶段研究，其中在前3个阶段提供所有食物和饮料，而在第四阶段建议但不提供饮食。 在第1阶段，所有受试者最初将接受5周的平均等体重美国饮食（15%蛋白质，35%脂肪; 15%饱和脂肪; 15%单不饱和（单）脂肪; 6%多不饱和（多）脂肪，150 mg胆固醇/1000卡路里和10 g/1000卡路里纤维）。 对于第2阶段，受试者将被平均随机分配至3种饮食中的一种，所有饮食均含有15%蛋白质、5%饱和脂肪和60 mg胆固醇/1000卡路里：1）高复合碳水化合物（CHO）：15%的脂肪，5%的单，5%的聚，和70%的CHO（主要是复合物，具有相对高的血糖指数）、16 g/1000 cal纤维和1.10 cal/gm的低膳食热量密度; 2）高单：与饮食1相同，除了脂肪含量为30（15%单）和55% CHO，其中CHO具有高血糖指数和高热量密度，1.25 cal/gm;和3）复合物：与饮食2相同，不同之处在于血糖指数较低和饮食热量密度较低（1.10 g/1000 cal）。 这些饮食将被随意给予，受试者可以使用200卡路里的砂锅菜来调整他们的卡路里水平，从维持体重所需卡路里的66%到133%，持续12周。 然后，受试者将在第3阶段的受控环境下继续接受这些相同的饮食，再持续5周，然后在非受控环境下持续1年（第4阶段），其中他们将接受饮食指导和菜单，但不接受食物。 将每周评估3次体重和血压，并在每个控制饮食期结束时以及长期随访期的3、6、9和12个月时，在空腹状态下评估3次血浆脂蛋白（LDL、HDL、残余物和Lp[a]）、葡萄糖、糖化血红蛋白和胰岛素水平，在进食状态下评估1次。 此外，将在所有阶段定期测量体重、身体能量消耗、体力活动、身体组成、人体测量学和代谢率。 我们的假设是，富含复合碳水化合物和低热量密度的限脂饮食和低热量密度和低血糖指数的复合饮食比高单一脂肪、高血糖指数和高热量密度的第二步饮食对CHD危险因素、体重、身体组成和能量消耗有更有利的影响。

Coronary heart disease (CHD) is a major cause of death and disability in our society. Obesity increases CHD risk by adversely affecting glucose, lipoproteins, and blood pressure. There is consensus that dietary saturated fat and cholesterol (C) restriction is beneficial for low density lipoprotein (LDL) lowering and CHD risk reduction, but there controversy about other aspects of the diet. We propose to examine the effects of three diets meeting National Cholesterol Education program Step 2 diet criteria on body weight and composition and on CHD risk factors (LDL C, HDL C, remnant lipoprotein C, Lp(a) C, insulin, glycosylated hemoglobin, glucose, and blood pressure) in the fasting and nonfasting state (4 hours after a meal) in 80 men and women (men greater than or equal to 50 and less than 65 years of age, women postmenopausal and less than 65) with LDL C values greater than or equal to 130 mg/dI and a body mass index greater than or equal to 28 and less than 38 kg/m2. A four phase study will be conducted in which all food and drink is provided during the first 3 phases, while diet is recommended but not provided in the fourth phase. In phase 1, all subjects will initially be placed on an average isoweight U.S. diet for 5 weeks (15 percent protein, 35 percent fat; 15 percent saturated fat; 15 percent monounsaturated (mono) fat; 6 percent polyunsaturated (poly) fat, with 150 mg of cholesterol/1000 calories and 10 g/1000 cal. of fiber). For phase 2, subjects will then be equally randomized to one of 3 diets, all containing 15 percent protein, 5 percent saturated fat and 60 mg of cholesterol/1000 calories: 1) high complex carbohydrate (CHO): 15 percent fat, 5 percent mono, 5 percent poly, and 70 percent CHO (mainly complex with relatively high glycemic index), 16 g/1000 cal of fiber, and low dietary caloric density of 1.10 cal/gm; 2) high mono: identical to diet 1 except that the fat content will be 30 percent (15 percent mono) and 55 percent CHO with CHO of high glycemic index and high caloric density, 1.25 cal/gm; and 3) composite: identical to diet 2 except that there will be lower glycemic index and low dietary caloric density of 1.10 g/1000 cal). These diets will be given ad libitum, and subjects can adjust their calorie level using 200 calorie casseroles from 66 percent to 133 percent of calories needed to maintain weight, for a 12 week period. Subjects will then be continued on these same diets isoweight for an additional 5 weeks under controlled circumstances in phase 3, and then for one year (phase 4) under uncontrolled circumstances where they will receive dietary instruction and menus, but not food. Body weight and blood pressure will be assessed three times per week, and plasma lipoproteins (LDL, HDL, remnants, and Lp[a]), glucose, glycosylated hemoglobin, and insulin levels will be assessed three times in the fasting state and once in the fed state at the end of each controlled dietary period and at 3, 6, 9, and 12 months in the long-term follow-up period. In addition, body weight, body energy expenditure, physical activity, body composition, anthropometics, and metabolic rate will be measured at regular intervals during all phases. Our hypothesis is that the fat-restricted diet rich in complex carbohydrate and low in caloric density and the composite diet low in caloric density and glycemic index will have a more favorable effect on CHD risk factors, body weight, body composition and energy expenditure than the Step 2 diet higher in mono fat, glycemic index, and caloric density.