A global study challenges the need to drink eight glasses of water daily, revealing that individual hydration needs vary widely and are not strictly tied to thirst.
Study challenges eight-glass water rule
A study published in Science in November 2022, led by Yosuke Yamada and John Speakman, measured the actual water turnover in the human body across 5,604 people from 23 countries. The study found that the commonly cited rule of drinking eight glasses of water per day, or about two liters, lacks solid experimental support and is largely driven by commercial marketing rather than physiological necessity.Water needs vary by age and gender
The research revealed that water needs vary significantly among individuals. On average, men aged 20 to 35 have a water turnover of 4.2 liters per day, while women aged 20 to 40 have a turnover of 3.3 liters. These figures decline with age, reaching approximately 2.5 liters by the age of 90. The study found that water turnover can vary by as much as double depending on individual profiles.Deuterium used to track water movement
The researchers used deuterium, a stable isotope of hydrogen, to track water movement in the body. This method, applied to participants ranging in age from eight days to 96 years, is considered the gold standard for measuring water turnover. The study indicates that factors other than thirst, such as energy expenditure and dietary water intake, play a significant role in determining individual water needs.
