Ravussin E, Harper I T, Rising R, Bogardus C
Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016.
Am J Physiol. 1991 Sep;261(3 Pt 1):E402-9. doi: 10.1152/ajpendo.1991.261.3.E402.
The doubly labeled water (2H2(18)O) method to assess energy expenditure in free-living conditions has been successfully validated against gas exchange measurements in lean healthy volunteers in both sedentary conditions and during sustained heavy exercise. However, no data are available on obese subjects. We therefore compared the 2H2(18)O method with indirect calorimetry (respiratory chamber) in 12 male subjects covering a wide range of body weight and composition (61-190 kg, 7-41% fat). Isotope pool sizes and elimination rates were calculated from 18O and 2H enrichments in baseline urine samples and in 7-h, 11.5-h, and daily postdose urine samples using the multipoint slope/intercept method. Results were corrected for isotopic fractionation. Mean 7-day energy expenditure in the respiratory chamber varied from 1,851 to 4,105 kcal/day. The doubly labeled water method tended to underestimate energy expenditure (-2.5 +/- 5.8%, not equal to 0, range -14 to +4%), with the larger underestimate observed in heavier and fatter subjects (r = -0.82 and -0.68, P less than 0.02, respectively). The underestimation in heavier subjects might be related to larger sequestration of deuterium during fat synthesis. In conclusion, the doubly labeled water method is a suitable and accurate method to measure energy expenditure in free-living conditions but might provide a slightly underestimated figure in fatter subjects.
在自由生活条件下评估能量消耗的双标水（2H2(18)O）法已在久坐状态和持续剧烈运动的瘦健康志愿者中，通过与气体交换测量结果对比而成功得到验证。然而，尚无关于肥胖受试者的数据。因此，我们在12名涵盖广泛体重和身体组成范围（61 - 190千克，7 - 41%脂肪）的男性受试者中，将双标水法与间接测热法（呼吸室法）进行了比较。使用多点斜率/截距法，根据基线尿液样本以及给药后7小时、11.5小时和每日尿液样本中的18O和2H富集情况计算同位素池大小和消除率。对结果进行了同位素分馏校正。呼吸室内7天的平均能量消耗在1851至4105千卡/天之间变化。双标水法往往会低估能量消耗（-2.5 +/- 5.8%，不等于0，范围为-14%至+4%），在体重较重和脂肪较多的受试者中观察到的低估幅度更大（r分别为-0.82和-0.68，P均小于0.02）。体重较重的受试者中出现的低估可能与脂肪合成过程中氘的更大潴留有关。总之，双标水法是在自由生活条件下测量能量消耗的一种合适且准确的方法，但在较胖的受试者中可能会提供略为低估的数据。
