As a kid, your parents are always telling you to drink more of it. In your 20s you down one between cocktails to stave off a hangover. As you get older you notice dry skin, under-eye circles and headaches creeping up when you don’t get enough of it. Gym rats carry around huge jugs of it, models swear by it as an essential piece of their beauty routine and a lack of it may just be the reason behind your daily afternoon slump.
As much as we glorify the beverage (rightly so) many of us aren’t getting enough: More than half of children and teenagers in the United States are not properly hydrated, according to a nationwide study from the Harvard T. H. Chan School of Public Health. The problem doesn’t stop when we enter adulthood: The Natural Hydration Council found that one in 10 consultations for tiredness and fatigue could be attributed to dehydration, and more than a third of the patients reported feeling better after drinking more water. The problem is, among the 300 general practitioners surveyed, just 4 percent believed their patients were aware of how to hydrate properly.
It may seem like a no-brainer — just drink more water. But do you know exactly how much you should be drinking?
We all know the eight-glasses-a-day rule, but is it something we should hang our hat on? While the goal certainly isn’t a bad one to aim for, the actual equation is more complicated.
“It is somewhat arbitrary as it doesn't take into account the size, activity, environment or diet of the individual,” says Dr. Barry Sears, leading authority on the dietary control of hormonal response and author of The Zone Diet.
So where did this guideline come from?
Dozens of factors can affect a person’s individual water needs, from exercising to sickness to the temperature outside.
“While no one knows for sure where the ‘8 x 8’ (which is eight, 8-ounce glasses of water) rule came from, it may have been adapted from the 1945 Food & Nutrition Board recommendation to drink about 2.5 liters of water each day,” explains Rima Kleiner, MS, RD and blogger at Dish on Fish. “The nice thing about the 8 x 8 water rule (which is about 1.9 L/day) is that it’s easy to remember, and it’s not too far off from the Institute of Medicine (IOM) general water recommendations of 13 cups (or 3 L) of water per day for men and 9 cups (or 2.2 L) of water per day for women.”
That being said, there are dozens of factors that can affect each person’s individual water needs, from exercising to sickness.
“There are lots of factors that impact our fluid needs,” says Kleiner. “If you are pregnant or losing fluids (whether through sweat, vomiting, diarrhea or nursing), you need to replenish those lost fluids. Exercise also increases our fluid needs. (Those engaging in intense training or exercise may need to replenish electrolytes and water.) The temperature outside also affects our fluid need. If it’s hot and/or humid, you are likely sweating (even if you don’t notice it), which means increased fluid needs. Illnesses (like fever, diarrhea or vomiting) result in loss of bodily fluids, which means you need to drink more fluids (and may need to replenish with electrolytes, as well). And if you’re an expectant or nursing mama, your body has an increased need for nutrients and fluids.”
While you may not be able to determine an exact number of glasses that will ensure you remain perfectly hydrated at all times, there are some key steps you can take to keep you out of the dehydrated zone.
The best indicator that you need to drink water? Thirst, says Dr. Sears. “The reason you have a sensation of thirst is because the lack of water alters the balance of salt in the blood and this imbalance causes a cascade of effects resulting in the desire (i.e. thirst) for greater hydration.”
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Essentially, thirst is a symptom of dehydration.
“Our thirst sensation doesn’t really appear until we are 1 [percent] or 2 percent dehydrated. By then dehydration is already setting in and starting to impact how our mind and body perform,” says Lawrence E. Armstrong, one of the studies’ lead scientists, director of the Human Performance Laboratory at the University of Connecticut and an international expert on hydration who has conducted research in the field for more than 20 years. “Dehydration affects all people, and staying properly hydrated is just as important for those who work all day at a computer as it is for marathon runners, who can lose up to 8 percent of their body weight as water when they compete.”
"Our thirst sensation doesn't really appear until we are 1 or 2 percent dehydrated. By then dehydration is already setting in and starting to impact how our mind and body perform."
If you feel thirsty, it’s your body’s way of saying it’s dehydrated, says Kleiner. “Other signs of dehydration include altered mood, dry eyes, headaches or dizziness, muscle cramping, fever or lack of sweat.”
There really is no magic number or formula for how much fluid you need every day, but the color of your urine is a pretty good indicator of where you stand on the hydration scale. “If your urine is colorless or pale yellow, you’re likely drinking an adequate amount of water," says Kleiner. "Mild dehydration may show itself in the form of bright or dark yellow urine. If your urine is darker than pale yellow or you’re feeling thirsty, then you need to drink some water.”
Sears agreed: “The best way [to tell if you're hydrated] is the color of your urine. If it's very pale in color, you are probably hydrated. The darker the color of the urine, the greater the hydration you require.”
One thing most of us fail to recognize is that our water intake isn’t only coming in a glass — the foods we eat make up a large chunk of our intake. “What wasn’t adapted was the part of the recommendation that suggested that most of this 2.5 liters would come from foods,” says Kleiner.
In fact, according to Kleiner about 20 percent of our total water intake comes from the food we eat. “Many vegetables and fruits are mostly comprised of water (some are more than 90 percent water), which really helps to contribute to our fluid intake and keep us hydrated,” she says. “And, all of those other beverages we consume (like milk, juice, beer, wine, even coffee, tea and soda) contribute to our fluid intake. But, don’t forget, other beverages (aside from water) contain calories.”
So now we know how to avoid dipping low on the hydration scale. But why should we care so much? You may be surprised by how much dehydration can affect your mental and physical health. Here are a few key areas that will take a hit when you don’t sip enough:
Skin: “Dehydration can make skin lose elasticity and suppleness, which may cause skin to look more wrinkled than it is,” said Kleiner. “Staying hydrated helps skin act as that protective barrier to the elements.”
Dry and non-supple skin is one of the easiest signs that we can see, agrees Sears: “Most of our internal water is lost through the skin. If you are not hydrated, the skin is the first organ to suffer by being overly dry and non supple.”
Energy: “Staying hydrated helps maintain our energy levels by keeping muscles energized. Plus, dehydration can manifest as fatigue or low energy, so staying hydrated will help prevent that,” says Kleiner.
Even mild dehydration can affect your mood, energy level and ability to think clearly.
What does water have to do with energy in the body? “Your cells need adequate hydration to optimize the production of energy from food,” explains Sears. “If you don't have adequate hydration in the cells, your ability to produce energy (such as ATP) is reduced and you feel fatigued.”
Even being mildly dehydrated can have effects on your mood, energy level and ability to think clearly, according to studies conducted at the University of Connecticut’s Human Performance Laboratory. So the next time that mid-afternoon slump hits, consider trading the trip to the vending machine for one to the water cooler.
Sleep: “There is little research on how dehydration may impact sleep, but if you’re experiencing muscle cramping, headaches or dizziness due to dehydration, chances are that you likely won’t be getting good quality of sleep,” says Kleiner. Plus, a study published in the British Journal of Nutrition found that male subjects experienced fatigue, tension and anxiety when mildly dehydrated. As we know, stress (and its symptoms) can affect our sleep quantity and quality.
Productivity: “The neurons in the brain require adequate hydration to maintain optimization transmission of neurotransmitters,” says Sears. Even mild dehydration can result in disorientation, dizziness and fuzzy thinking, added Kleiner.
A study published in The Journal of Nutrition found thatmild dehydration caused headaches, fatigue and difficulty concentrating. The female subjects also perceived tasks as more difficult when slightly dehydrated. So consider swapping that pre-meeting coffee for a glass of ice water to be the most alert.
Overall health: “While staying hydrated improves tangibles we can see (like the improved appearance of skin and high-quality athletic performance), hydration is perhaps more important for functions we can’t see,” says Kleiner. “Adequate fluid intake helps maintain our body-fluid balance, which is important for saliva production and maintaining body temperature. Staying hydrated also helps keep our kidneys functioning properly, so they can do their job of transporting waste products into and out of cells and preventing the buildup of blood urea nitrogen, which gets excreted in urine. Chronic dehydration can result in kidney stones. And, last but certainly not least, water helps maintain normal bowel movements, which can certainly influence your mood and energy levels.“
Convinced it’s time to start upping your intake? We thought so. Here are some super simple strategies for sipping more water throughout the day.
Every time you go to a new place, drink. A meeting, the gym, a bar? Time for a glass of water. When our BETTER team challenged themselves to increase their water intake they found this tactic particularly helpful. It’s easy to sip when you’re sitting at your desk. But when you’re running errands on the weekend, heading to the gym or meeting friends for happy hour it gets a little harder to remember to sip. Setting the simple goal of drinking every time you change locations is an easy way to remember.
Set an alarm reminding you to drink water. Another takeaway our team found helpful in their quest to hydration? Setting alarms to remind themselves to drink. If you’re not good at staying on top of setting the alarm, invest in a water bottle that does the work for you. Most of them have the added benefit of also tracking your water consumption, which one of our editors found helpful: “Being able to track how much water I'm drinking and assess how I'm feeling based on that has helped me realize that my body needs more water than I expected and that my afternoon headaches aren't from stress or a coffee (or three) too many, but were actually from being dehydrated,” Emily says.
Pair food with water. “Make sure to have a beverage with every meal and snack, so at least you know you’ll be getting fluids several times throughout the day,” says Kleiner.
Keep an eye on your skin – and body. “Keep looking at your skin and sensing how you feel as well as being aware of your thirst," said Sears. “If you are eating a lot of fruits and vegetables, instead of grains, starches and junk food, your body will tell you you're are OK relative to hydration and you will probably lose weight in the process.”
Eat more hydrating foods. “Eat more fruits and veggies and water-constituted foods like oatmeal,” suggests Kleiner. “Try adding at least one fruit and vegetable to every snack and meal. Add fruit to yogurt, smoothies or as a salsa to fish and chicken. Serve a salad and a vegetable alongside your whole grain and protein sources, like beans, seafood or chicken.”
Make your water fun! “Add berries, citrus fruits, apples and cinnamon, cucumbers and mint to your water bottle to add flavor without adding calories,” says Kleiner.