Zhang Na, He Hairong, Zhang Jianfen, Ma Guansheng
Department of Nutrition and Food Hygiene, School of Public Health, Peking University, 38 Xue Yuan Road, Hai Dian District, Beijing, 100191, China.
Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, 38 Xue Yuan Road, Hai Dian District, Beijing, 100191, China.
Nutr Metab (Lond). 2022 May 2;19(1):32. doi: 10.1186/s12986-022-00668-2.
Few studies on measuring human energy expenditure with the doubly labeled water method has been conducted in China. The sources and loss of water among human body have never been systematically evaluated. Less data can be available for the development of the recommendation on energy expenditure and water intake. The objective of this study was to determine the energy expenditure, water sources, and loss among young adults.
In this cross-sectional study, 25 participants were recruited. Double-labeled water was used to determine their energy expenditure. Water loss through skin evaporation and respiration of the lungs and water sources from metabolic water were calculated using corresponding formula, respectively. Water loss through excretion of urine was recorded and evaluated using "3-day, 24-h, real-time urine excretion record" method. All urine samples were collected and weighed in the 3 days. Water loss through excretion of feces was evaluated using "3-day, 24-h, real-time fecal-excretion record" method. All fecal samples were collected and tested by the direct drying method. Water sources from fluid intake were recorded by "7-day, 24-h, real-time fluid intake record" method. Water intake from food was calculated and tested by the weighing method combined with the duplicate portion method and the direct drying method in the 3 days.
The energy expenditure of males was 2187 kcal/d, and that of females was 1987 kcal/d. The median fluid intake, water intake from food, and metabolic water were 887, 1173 and 246 mL, respectively, which accounted for 38.8%, 50.3%, and 11.2% of total water sources. There was a gender difference in the percentage of metabolic water (Z = - 2.135, P = 0.033). The water loss through urine excretion, skin evaporation, respiration, and feces excretion was 1295, 172, 149 and 64 mL, respectively, which accounted for 76.5%, 10.3%, 9.5%, and 3.6% of the total water losses. Gender differences in the amount of water loss through respiration and skin evaporation were found (Z = - 4.125, P < 0.001; Z = - 3.723, P < 0.001).
Energy expenditure of male was higher than that of female. The first major water sources was water intake from food in this study, and the first major water loss was urine excretion. Trial registration The study was registered on the website of Chinese clinical trial registry, and the code of identification is ChiCTR1900028746.
在中国，很少有关于用双标水法测量人体能量消耗的研究。人体水分的来源和流失从未得到系统评估。关于能量消耗和水摄入量建议的制定可获取的数据较少。本研究的目的是确定年轻成年人的能量消耗、水分来源和流失情况。
在这项横断面研究中，招募了25名参与者。使用双标水法确定他们的能量消耗。分别使用相应公式计算通过皮肤蒸发和肺呼吸流失的水分以及代谢水产生的水分来源。使用“3天、24小时实时尿液排泄记录”方法记录并评估通过尿液排泄流失的水分。在这3天内收集所有尿液样本并称重。使用“3天、24小时实时粪便排泄记录”方法评估通过粪便排泄流失的水分。所有粪便样本均采用直接干燥法进行收集和检测。通过“7天、24小时实时液体摄入记录”方法记录液体摄入产生的水分来源。在这3天内，采用称重法结合双份食物法和直接干燥法计算并检测食物摄入的水分。
男性的能量消耗为2187千卡/天，女性为1987千卡/天。液体摄入量、食物摄入的水分和代谢水的中位数分别为887、1173和246毫升，分别占总水分来源的38.8%、50.3%和11.2%。代谢水的百分比存在性别差异（Z = -2.135，P = 0.033）。通过尿液排泄、皮肤蒸发、呼吸和粪便排泄流失的水分分别为1295、172、149和64毫升，分别占总水分流失的76.5%、10.3%、9.5%和3.6%。发现呼吸和皮肤蒸发流失的水量存在性别差异（Z = -4.125，P < 0.001；Z = -3.723，P < 0.001）。
男性的能量消耗高于女性。在本研究中，主要的水分来源是食物摄入的水分，主要的水分流失是尿液排泄。试验注册 该研究在中国临床试验注册中心网站上注册，识别码为ChiCTR1900028746。
