Do we really need to drink 8 glasses of water a day or is this just a myth? The British newspaper The Guardian asked an expert about this, and the answer was disappointing for water lovers.
Professor Lewis Halsey, Professor of Environmental Physiology at the University of Roehampton, UK, says: “Concern about the necessity of drinking sufficient amounts of water is overstated.”
Water is one of the necessities of life. Without water, humans can only survive for a few days. Water constitutes from 75% of body weight in infants to 55% in the elderly, and it is necessary to maintain cellular balance and life.
“It’s complicated,” Halsey says. “Obviously people can become dehydrated. Our bodies are wired to have a high rate of water turnover: we sweat to keep cool, so we need to replenish those fluids. But we can, at least in the short or even medium term.” “We can lose a lot of fluids and still be fine.”
How much water do we need?
Halsey, who researches the effect of sweating and drinking on body temperature, says the amount of water each person needs varies. Larger, more active people usually need larger amounts.
If someone has very low levels of body fat – whether because they are very thin or have high muscle mass – they need more water because muscle contains more water than fat, so their tissues need more hydration.
People who live in less humid climates also need more water, because they lose more water through breathing. Since 20-30% of the water we consume comes from food, if your diet contains high-calorie-dense foods, you may need to drink more. “Part of the reason why food is so dense is because it has a low water content,” Halsey adds.
Drink when you are thirsty unless you are very old
So, how do we know if we’re drinking enough water? “Drink when you’re thirsty,” says Halsey, rather than trying to reach a specific goal. The only exception for him is the elderly: “Usually, they have a less sense of thirst, and therefore are more susceptible to chronic dehydration.”
One thing Halsey stresses that we all shouldn’t feel is obligatory is that we should drink water consistently throughout the day: “The body is perfectly capable of handling intermittent doses of water.”