Before you read this article, can I just check you’ve drunk enough water today? You might want to refill your bottle because, remember, if you wait until you feel thirsty, you may already be dehydrated. No one is sure where this advice came from, but it’s all over the internet.
“Nowadays this is not considered sensible,” says Stuart Galloway, an associate professor in physiology, exercise and nutrition at the University of Stirling. “As humans, we have this homeostatic system, so when we need water, we feel thirsty.” Drinking when you are thirsty, he says, maintains your body’s water level within about 1-2% of its ideal state. “For most people, this is absolutely fine. Even for athletes, a loss of around 1% is considered to have negligible impact upon performance. So, although thirst may not kick in until you have lost some body water, this is not necessarily a bad thing.”
As we get older, our sense of thirst can get fuzzier and that is when dehydration can become a threat. It is a similar story for children, too. So perhaps the advice to drink water before you feel thirsty was originally aimed at parents and the elderly but now healthy adults are putting away gallons of water in a quest to be their best selves.
There is a dearth of facts when it comes to hydration. Pharmaceutical companies aren’t interested in researching the benefits of a free resource and dehydration isn’t a pressing public health issue requiring government funding. This leaves a profitable grey area for the drinks industry to exploit.
Water is, it would have us believe, a purifying fast-track to glowing skin, bright eyes and bags of energy. Galloway says detoxing with water is “a load of rubbish. Your kidneys do a very good job of sorting out what you need to retain and what you need to get rid of.”
Will water make your skin better? While dehydration isn’t good for your skin, says Bav Shergill, a consultant dermatologist and honorary senior lecturer at the University of Manchester, “once you hit a certain level of fluid intake, providing you are healthy, any excess water will be peed out.”
That is, unless you drink more than you can pee. Amanda Burls, an emeritus professor of public health at City, University of London, warns that drinking too much water can kill. Water intoxication occurs when the amount of electrolytes in the body becomes imbalanced by excessive water intake, disrupting brain function.
Dehydration is said to be the most common cause of headaches and in 2015, Burls wrote a critical appraisal of the evidence. She concluded: “Chronic mild dehydration may trigger headaches. Increased water intake could help. A small trial shows modest benefit; however, a larger, methodologically sound, randomised controlled trial is needed to confirm efficacy.” There is that grey area again.
In the US, popular advice is to drink eight, 8-ounce glasses of water – about 2 litres – a day: the “8x8 rule”that originated from a recommendation by the nutritionist Dr Fredrick J Stare in 1974 (he actually suggested six to eight glasses).
In the UK, the NHS recommends six to eight glasses, or up to 1.2 litres of “fluids” daily, pointing out that we obtain fluids from food. But it is the 8x8 rule that has become a health-goal meme with “the 8x8 challenge”.
How much you need to drink is governed by how active you are, the weather and your physiology. Tellingly, if you seek water-consumption advice from a quietly reputable US source such as Harvard Medical School, instead of the 8x8 rule, you get “four to six cups” a day for healthy adults and all beverages count, even diuretics such as coffee, tea and booze. Don’t they make us pee more so we end up dehydrated?
In 2016, Galloway tested the hydrating potential of a range of drinks and found a litre of beer was no less hydrating than a litre of water. Similarly, a litre of instant coffee, containing 212mg of caffeine, was as hydrating as water. Milk was even more hydrating, and effective as a hydration solution for people with diarrhoea. While not a green-light to binge on high-calorie drinks, it’s good to know that a cup of tea or half a lager still count as water intake.
How many of us are seriously dehydrated? No one knows but Galloway once studied fluid intake among workers in a Cardiff call centre and found that, to keep their ratings up, many would restrict their fluid intake to avoid loo breaks. “We imagine similar behaviour with long-distance lorry drivers,” he says. If we’re ingesting enough water, he adds, we should probably be going to the loo “somewhere between five and seven times a day”.
Try as we may, we've never been able to guzzle down six to eight glasses of water per day. But is that even necessary?As SELF reported in May, part of the problem with the famous rule of eight 8-ounce glasses a...
Try as we may, we've never been able to guzzle down six to eight glasses of water per day. But is that even necessary?
As SELF reported in May, part of the problem with the famous rule of eight 8-ounce glasses a day is that it fails to account for the water we get naturally through our diet.
And in a recent editorial, a general practitioner from Scotland claims the age-old advice to drink six to eight cups of water is "nonsense."
So how much water do you really need?
In other words, four cups of fluid throughout the day (through food and liquids) might be enough for some people (particularly those who exist almost entirely indoors, and who barely move off the couch), while others might need 10 cups or more.
The bottom line: There's no cut-and-dry answer regarding how much total water each of us needs. So instead of fretting about whether you're guzzling enough H2O, Stokes recommends making sure you get enough fluid (in all its forms) to stay hydrated.
Here's how:
Don't fixate on how many glasses you chug: Most of us think of a glass when the experts tell us to drink a cup. A cup is only 8 ounces; some glasses are 16 ounces, or more. Drink three 16-ounce glasses (one with breakfast, one with lunch and one with dinner) and you've already met the lower end of the so-called standard.
Eat water-rich foods: Hate water and can't stomach three glasses a day? Load up on water-rich foods like yogurt, grapefruit, lettuce, broccoli and watermelon (all of which have a water content of 85 percent or more)! Soup, milk and even ice pops are good options, too.
Check your pee: If it's pale or straw-colored, chances are you're adequately hydrated. If it's dark yellow or orange, well, you should probably hit the water cooler. Aim for even more fluids if you're active, if it's hot outside or both. Women should drink an additional 8 to 16 ounces of water, or an electrolyte-infused beverage, for every half hour they sweat through activity and heat.
Concerned about getting water-logged? Unless you're training for a marathon, elderly or hospitalized with a life-threatening condition or guzzling gallons of water in one sitting, hyponatremia (or overhydration) is nearly impossible, says Stokes. If you are an athlete in training or if you play some seriously demanding sports, drinking fluids that contain electrolytes (instead of plain water) will help protect you from the condition.
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