Water is essential for sustaining life and maintaining health. The human body relies on water to transport nutrients and waste products, lubricate joints, regulate body temperature, and preserve tissue structure. International research has shown that losing just 2% of body weight through water loss can impair physiological functions and reduce response capacity. Adequate water intake plays a crucial protective role in health: it helps regulate body weight, lowers the risk of chronic diseases such as cardiovascular and cerebrovascular conditions, and supports cognitive function.
However, the common recommendation to drink eight cups of water per day lacks strong scientific evidence. Most national hydration guidelines are based on average population intake, and personalized water intake recommendations have yet to be fully developed.
In this study, the investigators will use the deuterium dilution technique to measure water turnover in volunteers. Body composition will be assessed using the TANITA MC-780, while a seven-day fluid intake diary will track daily water consumption. Physical activity levels will be monitored using GT3 devices, and environmental data-including altitude, temperature, and humidity-will be collected based on participants' locations.
The goal of this study is to collect comprehensive data on the physiological traits, environmental influences, and hydration needs of the Chinese population. This will allow for refinement and optimization of current prediction equations for water requirements. Ultimately, the investigators aim to develop a new, individualized water intake algorithm tailored to the Chinese population by quantifying the proportion of water intake relative to total water requirements.
Stable body weight over the past year
Ability to perform normal physical activities
History of chronic diseases such as diabetes, liver disease, kidney disease, or any other conditions that may affect fluid metabolism
Use of diuretics or other medications that influence urine output
Pregnancy or breastfeeding
The study population consisted of healthy individuals with stable body weight over the past year and the ability to engage in normal physical activities. Participants had no history of chronic diseases, were not taking diuretics or other medications that affect urine output, and female participants were neither pregnant nor breastfeeding.
Cohort
Cross-sectional
Not listed
6
Trial groupsSee each trial group below.
Height
Height in meters (m) will be measured using the SECA 217 stable stadiometer. Subjects will be measured without shoes.
Body weight
Body weight in kilograms (kg) will be measured using the TANITA MC-780 device. Participants will be barefoot and dressed in light clothing during the measurement.
Body composition
The TANITA (TANITA MC-780) device will be used to measure fat mass (in kilograms, kg) as a primary indicator of body composition. Participants will be asked to remove all metal accessories and wear light clothing during the measurement.
Body water
Body water in kilograms will be measured by deuterium dilution. Subjects will attend the lab after an overnight fast and provide a baseline urine sample. They will then drink a dose of deuterated water based on their body weight. Urine samples will be collected at 4 hours after dosing, and 7 days after dosing, to measure the level of deuterium isotope in the body relative to the baseline. The increase in deuterium concentration allows for the calculation of total body water based on the dilution principle.
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