Le Carvennec Marie, Fagour Cédric, Adenis-Lamarre Emilie, Perlemoine Caroline, Gin Henri, Rigalleau Vincent
Nutrition-Diabétologie, USN, Hôpital Haut-Lévêque, Avenue de Magellan, 33600 Pessac, France.
Obesity (Silver Spring). 2007 Jan;15(1):78-84. doi: 10.1038/oby.2007.533.
We investigated whether air displacement plethysmography (ADP) could detect small changes in body composition of obese subjects with alterations in hydration.
Ten obese subjects (mean BMI, 39.3 +/- 2.8 kg/m2) entered the ADP chamber without and with oil (1, 2, or 4 liters), water (1, 2, or 4 liters), or mixed (1 liter oil + 1 liter water or 2 liters oil + 2 liters water) loads. Real and measured changes in body composition were compared by regression analysis and Bland-Altman procedures.
The ADP-measured changes in volume did not differ from the real values and were strongly correlated with them (r = 0.98). In all cases, loads of differing composition and similar volume led to different values of fat, fat-free mass, and percentage fat. Water was detected as increased fat-free mass only with loads of > or =2 liters, most of the water being falsely detected as increased fat mass. The observed changes were correlated with the real ones for fat mass (r = 0.68; p < 0.0001), fat-free mass (r = 0.66; p < 0.0001), and percentage fat (r = 0.61; p < 0.0001), but fat mass changes were overestimated by approximately 1 kg, and fat-free mass changes were underestimated by approximately 1 kg. This underestimation increased with the highest water loads, as shown by the Bland-Altman plot (r = -0.27; p < 0.05). Percentage fat changes were overestimated by 0.8% (p < 0.001); the magnitude of the error was correlated with the weight of the water load (r = 0.62; p < 0.0001).
ADP accurately measures changes in body volume, discriminating small changes in body composition. It overestimates changes in adiposity, as most of the increased hydration is detected as an enlarged fat mass.
我们研究了空气置换体积描记法（ADP）能否检测肥胖受试者在水合状态改变时身体成分的微小变化。
10名肥胖受试者（平均BMI为39.3±2.8kg/m²）进入ADP舱，分别在无负荷、有油（1、2或4升）、水（1、2或4升）或混合负荷（1升油 + 1升水或2升油 + 2升水）的情况下进行检测。通过回归分析和布兰德-奥特曼方法比较身体成分的实际变化和测量变化。
ADP测量的体积变化与实际值无差异，且与实际值高度相关（r = 0.98）。在所有情况下，不同成分但体积相似的负荷导致脂肪、去脂体重和脂肪百分比的不同值。仅在负荷≥2升时，水被检测为去脂体重增加，大部分水被错误地检测为脂肪量增加。观察到的脂肪量（r = 0.68；p < 0.0001）、去脂体重（r = 0.66；p < 0.0001）和脂肪百分比（r = 0.61；p < 0.0001）变化与实际变化相关，但脂肪量变化被高估约1kg，去脂体重变化被低估约1kg。如布兰德-奥特曼图所示，这种低估随着最高水负荷而增加（r = -0.27；p < 0.05）。脂肪百分比变化被高估0.8%（p < 0.001）；误差大小与水负荷重量相关（r = 0.62；p < 0.0001）。
ADP能准确测量身体体积变化，区分身体成分的微小变化。它高估了肥胖程度的变化，因为大部分水合增加被检测为脂肪量增加。
