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This is How Much Water You Should Actually Be Drinking Each Day

It's recommended you drink about two liters of water per day, but a new study suggests it may be less.

By Monica Cull
Nov 30, 2022 3:00 PMNov 30, 2022 4:14 PM
drinking water


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Increasing your daily water intake can have numerous health benefits like improved mood, focus and digestion health. It may even help shed unwanted pounds. But what if we didn't need to consume as much water as we thought?

The typical recommendation for daily water intake is eight glasses that are 8 ounces or about two liters daily. However, a new study published in Science suggests we may not need as much as we think. 

According to John Speakman of the Chinese Academy of Sciences and the University of Aberdeen, while water intake is vital, it isn't easy to objectively measure how much each person should consume daily. 

Read more: Can Drinking Water Really Help You Lose Weight?

Water Turnover

For this study, researchers analyzed water turnover in 5,604 male and female-bodied people from 23 different countries, with ages ranging from eight days to 96 years. According to a press release, water turnover is similar to water requirements and refers to replacing water in the human body throughout a day or period. 

Not surprisingly, researchers found that water turnover was higher in hot and humid environments and at higher altitudes. Athletes and those who were more physically active, along with those who were pregnant and breastfeeding, also had a higher water turnover rate. 

Researchers also found that higher turnover stemmed from higher energy expenditure. According to the study, males aged 20 to 35 saw some of the highest turnover rates and also experienced the highest energy expenditure. Their water turnover rate averaged 4.2 liters per day. However, as age increased, water turnover decreased. Males in their 90s had a water turnover rate of 2.5 liters per day. 

The water turnover rate for females aged 20 to 40 was 3.3 liters per day and 2.5 liters per day at age 90.

In developing countries, there was a higher water turnover rate compared to those in developed countries. According to a press release, this is because developed countries have air conditioning and heating that help prevent exposure to the elements. 

Required Water

The study authors noted that water turnover differs from the required amount of drinking water. Though a male may have a water turnover rate of 4.2 liters per day, this does not mean they need to consume 4.2 liters of water per day. 

According to the study, about 15 percent of the 4.2 liters reflects surface water exchange and water produced metabolically, which means that the actual required intake is about 3.6 liters per day. As many foods also contain water, the human body can gain water intake from eating. Though, researchers had difficulties determining the exact drinking water requirement after food. 

However, researchers estimated that for a typical male in their 20s living in the U.S. or Europe, more than half of the 3.6 liters of daily water comes from food. This means the required water intake would be about 1.5 to 1.8 liters per day. For females of the same age, daily water intake would be about 1.3 to 1.4 liters per day. This amount is likely lower for the elderly and higher for athletes, those who are pregnant and those living in warmer climates. 

"Figuring out how much water humans require is significant due to explosive population growth and growing climate change. Water turnover is related to many health parameters like physical activity, body fat percent, etc., making it a new potential biomarker for metabolic health," says Zhang Xueying from the Shenzhen Institute of Advanced Technology and co-author of the study in a press release. 

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