Division of Nutrition, St. John's Research Institute, St. John's National Academy of Health Sciences, Bengaluru, Karnataka, India.
Division of Nutrition, St. John's Research Institute, St. John's National Academy of Health Sciences, Bengaluru, Karnataka, India; Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
J Nutr. 2023 Feb;153(2):435-442. doi: 10.1016/j.tjnut.2022.12.025. Epub 2022 Dec 28.
Accurate methods are needed to measure body fat mass (FM), particularly in South Asian children who are thought to have greater adiposity for a given body size. The accuracy of simple 2-compartment (2C) models of measuring FM depends on the primary measurement of the fat free mass (FFM) and the validity of assumed constants for FFM hydration and density. These have not been measured in this particular ethnic group.
To measure FFM hydration and density in South Indian children using a 4-compartment (4C) model and to compare FM estimates from this 4C-model with 2C-model-based estimates from hydrometry and densitometry, using literature-reported FFM hydration and density in children.
This study included 299 children (45% boys), aged 6-16 y from Bengaluru, India. Total body water (TBW), bone mineral content (BMC), and body volume were measured using deuterium dilution, dual-energy X-ray absorptiometry, and air displacement plethysmography, respectively, to calculate the FFM hydration and density, and the FM using 4C and 2C models. The agreement between FM estimates from 2C and 4C models was also evaluated.
Mean FFM hydration and density were 74.2% ± 2.1% and 71.4% ± 2.0% and 1.095 ± 0.008 kg/L and 1.105 ± 0.008 kg/L in boys and girls respectively, which were significantly different from published values. Using the presently estimated constants, the mean hydrometry-based FM (as % body weight) estimates decreased by 3.5% but increased by 5.2% for densitometry-based 2C methods. When 2C-FM (using previously reported FFM hydration and density) were compared with 4C-FM estimates, the mean difference was -1.1 ± 0.9 kg for hydrometry and 1.6 ± 1.1 kg for densitometry.
Previously published constants of hydration and density of FFM may induce errors of -12% to +17% in FM (kg) when using different 2C models in comparison to the 4C models in Indian children. J Nutr 20xx;x:xx.
需要准确的方法来测量体脂肪量（FM），特别是在南亚儿童中，他们的身体大小被认为有更大的肥胖度。简单的双 compartment（2C）模型测量 FM 的准确性取决于对无脂肪质量（FFM）的主要测量以及对 FFM 水合和密度的假定常数的有效性。这些在特定的族群中并没有被测量。
使用四 compartment（4C）模型测量南印度儿童的 FFM 水合和密度，并比较来自 4C 模型的 FM 估计值与来自水容量法和密度计法的 2C 模型基于文献报告的儿童 FFM 水合和密度的估计值。
本研究包括 299 名年龄在 6-16 岁的来自印度班加罗尔的儿童（45%为男孩）。总身体水（TBW）、骨矿物质含量（BMC）和身体体积分别使用氘稀释、双能 X 射线吸收法和空气置换体描记法进行测量，以计算 FFM 水合和密度以及使用 4C 和 2C 模型的 FM。还评估了来自 2C 和 4C 模型的 FM 估计值之间的一致性。
男孩和女孩的 FFM 水合平均值分别为 74.2%±2.1%和 71.4%±2.0%，密度平均值分别为 71.4%±2.0%和 71.4%±2.0%，1.095±0.008kg/L 和 1.105±0.008kg/L，与文献值有显著差异。使用目前估计的常数，水容量法基于 FM（占体重的百分比）的平均估计值下降了 3.5%，但密度计法基于 2C 方法的估计值增加了 5.2%。当比较 2C-FM（使用以前报告的 FFM 水合和密度）与 4C-FM 估计值时，水容量法的平均差值为-1.1±0.9kg，密度计法为 1.6±1.1kg。
在印度儿童中，与 4C 模型相比，使用不同的 2C 模型时，以前发表的 FFM 水合和密度常数可能会导致 FM（kg）的误差在-12%到+17%之间。
