DIETARY FAT, CARBOHYDRATE BALANCE AND WEIGHT MAINTENANCE

当饮食提供了足够的蛋白质时，体重维持是 主要由摄入和氧化之间的相互作用决定 碳水化合物和脂肪。因为人体的糖原储备只包含 大约1/100的能量储存为身体脂肪，代谢调节和 内分泌信号准备优先调整 碳水化合物氧化为碳水化合物摄入量。此外，我们发现在 随意喂食的小鼠对食物摄入量的调整反应更快 对碳水化合物的偏离而不是对脂肪平衡的偏离。还没有 保持体重还要求脂肪的氧化程度与之相称 有脂肪摄入量。在脂肪含量很高的饮食中， 糖原储备保持和/或增加的比率 脂肪组织块的大小是提高循环自由所必需的 足以导致代谢燃料氧化的脂肪酸水平 混合脂肪与碳水化合物的比例与饮食中的比例相当。我们 因此将决定相对比例的变化如何 饮食中不同类型的脂肪和碳水化合物会改变身体 在广告中达到保持体重的平台期的成分 Libitum给小鼠喂食。饮食杠杆的可逆性将是 通过使用身体对身体脂肪含量的序贯评估进行研究 瘦小鼠和肥胖小鼠的密度测量。 通过测量每日营养摄入量和24小时呼吸交换， 我们将测定碳水化合物和脂肪的氧化，以及它们的 连续多天的每日余额。这允许第一个 是时候评估能量消耗和食物摄入量的变化，以及 RQ的变化有助于产生“纠正反应”， 通过补偿暂时的体重来保持体重 偏离糖原、命运和能量平衡。影响 激素(如皮质酮、甲状腺素)、运动和 将研究减肥药。 通过为动物提供诱导高新鲜率的饲料 脂肪生成，或通过将它们暴露在不同程度的寒冷中，我们将 试图证明能源支出的增加并不意味着 正如人们普遍认为的那样，必然会导致体重减轻。 自发的身体活动对能量消耗的影响将是 测量，除其他外，以获得进一步的活体数据 当碳水化合物或命运被氧化时，“净ATP产生量”的差异。 拟议调查的主要目标是：(A)确定 饮食中脂肪含量和碳水化合物性质的影响 在自由进食下消耗稳定状态的身体成分 条件，以及(B)说明偏差的相对重要性 从碳水化合物、脂肪或能量平衡中自发地 对食物摄入量的调节。随着时间的推移，这可能有助于解释为什么 减少饮食中的脂肪含量有助于保持体重 肥胖程度较低，特别是那些没有身体状况的人 激活。

When the diet provides more than enough protein, weight maintenance is determined primarily by interactions between intake and oxidation of carbohydrates and fats. Since the body's glycogen reserves contain only about 1/100 of the energy stored as body fat, metabolic regulation and endocrine signals are poised to give priority to the adjustment of carbohydrate oxidation to carbohydrate intake. Furthermore, we found in ad libitum fed mice that the adjustment of food intake is more responsive to deviations from the carbohydrate than from the fat balance. Yet weight maintenance requires as well that fat oxidation be commensurate with fat intake. On diets with a substantial fat content, decreases in the rate within which glycogen reserves are kept an/or increases in the size of the adipose tissue mass are necessary to raise circulating free fatty acid levels enough to bring about the oxidation of a metabolic fuel mix with a fat-to-carbohydrate ratio equivalent to that of the diet. We will therefore determine how alterations of the relative proportions of different types of fats and carbohydrates in the diet modify the body composition for which the plateau of weight maintenance is reached in ad libitum fed mice. The reversibility of the dietary leverage will be studied by sequential assessment of the body fat content using body density measurements in lean and obese strains of mice. By measuring daily nutrient intake and the 24 hour respiratory exchange, we will determine the oxidation of carbohydrate and of fat, and their daily balances over many consecutive days. This allows for the first time to assess how changes in energy expenditure and in food intake, and of variations in the RQ contribute to the "corrective responses" which bring about maintenance of body weight, by compensating for temporary deviations from the glycogen, fate and energy balances. The influence thereon of hormones (e.g. corticosterone, thyroxin), of exercise, and of weight reducing drugs will be studied. By providing animals with diets inducing high rates of de novo lipogenesis, or by exposing them to variable degrees of cold, we will attempt to demonstrate that increases in energy expenditure do not necessarily lead to a reduction i body weight, as generally believed. The effect of spontaneous physical activity on energy expenditure will be measured, in order, among other, to obtain further in vivo data on differences in "net ATP yields" when carbohydrate or fate is oxidized. The main goals of the proposed investigations are (a) to characterize the impact of the diet's fat content and of the nature of the carbohydrates consumed on steady-state body composition under ad libitum feeding conditions, and (b) to delineate the relative importance of deviations from the carbohydrate, fat or energy balances int he spontaneous regulation of food intake. In time this may contribute to explain why a reduction in the diet's fat content facilitates weight maintenance at a lower level of adiposity, particularly individuals who are not physically active.