Bruce A C, McNurlan M A, McHardy K C, Broom J, Buchanan K D, Calder A G, Milne E, McGaw B A, Garlick P J, James W P
Rowett Research Institute, Bucksburn, Aberdeen, UK.
Int J Obes. 1990 Jul;14(7):631-46.
The immediate metabolic response to eating has been compared in a group of grossly obese subjects (W/H2 = 45) with that in lean controls (W/H2 = 22). Dietary intake of energy for obese subjects was based on their estimated basal energy expenditure for ideal body weight (given at an hourly rate of 3 X BMR over a 4-h period). Lean subjects were measured twice: control 1 with the same intake of energy as the obese in terms of ideal body weight and control 2 with the same energy intake in relation to each subject's measured resting energy expenditure (2.2 X REE). The changes in energy expenditure and nutrient disposal with the onset of eating have been assessed by a method of combined respiratory gas analysis and intravenous infusion of 13C-labelled leucine. Leucine kinetics were used to quantitate rapid changes in protein oxidation and to assess protein synthesis and degradation. 1) Total energy expenditure was 20-30 per cent greater in obese subjects than lean subjects in fasting and feeding. Energy expenditure expressed per kg fat-free mass, from D2O dilution, was similar in obese and lean subjects in both fasting (5.8 v. 5.5 kJ/kg FFM/h) and feeding [6.7 v. 6.3 (Control 2) kJ/kg FFM/h]. 2) The onset of eating was associated with increased carbohydrate and protein oxidation with decreased fat oxidation in both lean and obese individuals. In obese subjects, however, both the decrease in fat oxidation and the increase in protein oxidation were significantly smaller (P less than 0.05) than the corresponding increments in lean subjects (Control 2). 3) The rate of protein synthesis was significantly (P less than 0.05) higher in obese subjects both in the fasting state (99 v. 84 mumols leucine/kg FFM/h) and in the fed state [94 v. 67 (Control 2) mumols leucine/kg FFM/h]. The rate of protein degradation was also higher in obese individuals in fasting (117 +/- 6 v. 106 +/- 4 mumol leucine/kg FFM/h) and feeding [65 +/- 4 v. 54 +/- 6 (Control 2) mumol leucine/kg FFM/h] though these differences are not statistically significant (P greater than 0.05). 4) The observed differences between obese and lean individuals in protein and energy metabolism in the fasted state and in the immediate response to eating do not support a hypothesis of greater metabolic efficiency in obesity.
研究人员将一组严重肥胖受试者（体重指数W/H2 = 45）进食后的即时代谢反应与瘦体重对照组（体重指数W/H2 = 22）进行了比较。肥胖受试者的饮食能量摄入量基于其理想体重的估计基础能量消耗（按4小时内每小时3倍基础代谢率计算）。对瘦体重受试者进行了两次测量：对照组1的能量摄入量按理想体重计算与肥胖受试者相同，对照组2的能量摄入量按每个受试者测量的静息能量消耗计算（2.2倍静息能量消耗）。通过联合呼吸气体分析和静脉输注13C标记亮氨酸的方法评估了进食开始后能量消耗和营养物质代谢的变化。亮氨酸动力学用于定量蛋白质氧化的快速变化，并评估蛋白质合成和降解。1）在禁食和进食状态下，肥胖受试者的总能量消耗比瘦体重受试者高20% - 30%。通过重水稀释法计算，每千克去脂体重的能量消耗在肥胖和瘦体重受试者的禁食状态下相似（分别为5.8和5.5千焦/千克去脂体重/小时），在进食状态下也相似[分别为6.7和6.3（对照组2）千焦/千克去脂体重/小时]。2）进食开始后，瘦体重和肥胖个体的碳水化合物和蛋白质氧化增加，脂肪氧化减少。然而，在肥胖受试者中，脂肪氧化的减少和蛋白质氧化的增加均显著小于瘦体重受试者（对照组2）（P < 0.05）。3）肥胖受试者在禁食状态下（99对84微摩尔亮氨酸/千克去脂体重/小时）和进食状态下[94对67（对照组2）微摩尔亮氨酸/千克去脂体重/小时]的蛋白质合成速率均显著更高（P < 0.05）。肥胖个体在禁食（117±6对106±4微摩尔亮氨酸/千克去脂体重/小时）和进食状态下[65±4对54±6（对照组2）微摩尔亮氨酸/千克去脂体重/小时]的蛋白质降解速率也更高，尽管这些差异无统计学意义（P > 0.05）。4）肥胖和瘦体重个体在禁食状态以及进食后的即时反应中，蛋白质和能量代谢的差异并不支持肥胖者代谢效率更高的假说。
