No, we no longer have to drink two liters of water a day: what is recommended now?

Five, between two and three fish a week, about 500 grams of meat a week… and two liters of water a day.

These are recommendations that, for years, have been widely defended by nutrition specialists. However, a new study published in the scientific journal says goodbye to the popular belief of eight glasses of water a day.

The research, which has been led by Professor dale schoelleremeritus professor of nutritional sciences at the University of Wisconsin–Madison (United States), has analyzed more than 5,600 people, from newborns to 96 years, from 23 different countries.

The most widespread recommendation until now was to drink two liters of water daily freepik

And, as the lead author explains, “this work is the best we’ve done so far to measure the amount of water people actually consume on a daily basis (the turnover of water in and out of the body) and the main factors driving the water rotation.

• “Science has never supported the idea of ​​eight glasses as an adequate guideline, if only because it confuses the total volume of water with drinking water, while much of the water comes from the food that is consumed.”

And it is that, two liters of water a day, or what is the same, about eight glasses approximately, “could be too high a recommendation, if the needs of most people are taken into account.”

So how many liters of water do you have to drink?

This new study does not intend to establish a new guideline to establish the liters of water that must be drunk daily, because there is a set of physical, atmospheric and genetic conditions that make us drink more or less. “There are also those who drink up to 10 liters a day,” stresses Schoeller.

The not only depends on what we drink, but also on the food we eat. A balance dietand mainly Mediterranean, based on vegetables, fish, pasta, rice and meat, will allow us to obtain approximately 50% of the amount of water our body needs.

Thus, the researchers emphasize, only between 1.5 and 1.8 liters of water per day is needed (for a person with moderate physical activity and without any chronic pathology).

Men and women do not need the same hydration

Newborns are the people who need the most water. In addition to infants, athletes, with intense physical activity, and pregnant women, need more hydration.

• “Determining how much water humans consume is increasingly important due to population growth and increasing climate change,” he says. Yosuke Yamadafrom the National Institute of Biomedical Innovation, Health and Nutrition of Japan.

The hydration that our body needs depends on several factors such as physical activity or body weight. freepik

“Since water turnover is related to other important indicators of health, such as physical activity and body fat percentage, it has potential as a biomarker of metabolic health.”

However, other things being equal, the need for water between men and women differs around half a liter. The results of this research, recently published, estimate that a 20-year-old man (not a professional athlete) who weighs 70 kilos, and who lives in an area with a relative humidity of 50%, ingests and loses 3.2 liters of water up to date.

In contrast, a woman of the same age and activity level, and who also lives in the same weather conditions, would lose about 2.7 liters of water. If the environmental humidity is intensified by 50%, the hydration needs will increase by 0.3 liters.

And if energy expenditure is doubled, the amount of water needed by the body increases by one more liter.

For this reason, there is no general recommendation for how many glasses of water we should consume daily, since it will depend on physical activity, the area in which we live, the amount of fruits and vegetables consumed (and the percentage of water they have) and energy expenditure.