Get access to everything we publish when you sign up for Outside+.
Your body is made up of about 60 to 70 percent water, and although you could live several weeks without food, you’ll only survive a matter of days without water. This is because water is involved in just about every metabolic and cellular function you have — transporting nutrients and oxygen, lubricating joints and regulating body temperature.
So you can see where dehydration is problematic, and in fact, just a two percent drop in water can result in impaired cognitive performance, headaches and fatigue. Dehydration also can affect mood, according to a study published in The Journal of Nutrition, causing irritability, lethargy and even anger. For athletes who often lose 6 to 10 percent of their water weight via sweat, dehydration can alter body temperature control, reduce motivation, and make exercise feel more difficult both mentally and physically.
Beyond its necessity for existence, water is also associated with weight loss and an increase in metabolism. One study found that drinking a half-liter (17 ounces) of water increased metabolism up to 30 percent for 90 minutes following ingestion. Proper hydration also can help maximize performance and reduce the oxidative stress that occurs during high-intensity exercise.
Water, Water Everywhere
Now comes the hard part: Which water should you drink? There are so many kinds available and so many conflicting opinions on what to drink and when that choosing a water has become as complicated as string theory. Here are the deets on some of the trendiest waters available today — what they are, what they aren’t and what they may or may not do — along with some hard research that either backs or benches them.
We are lucky in the Western world to have access to clean drinking water — many other countries can’t say the same — yet people are still quick to dismiss tap water as an acceptable way to hydrate these days. Tap water is typically treated with fluoride and chlorine, which can alter the taste quite a bit, and is monitored by the Environmental Protection Agency, which identifies contaminants in drinking water and sets limits on the amounts of certain contaminants that it deems as safe for consumption. However, some Americans live in places where contaminants may exceed the legal limit, according to the Environmental Working Group, and most notably in more rural and low-income areas. But tap water is still usable, and if you balk at the idea of any “contaminants” floating around in your water, invest in a good water filtration system to remove many of the particulates and chemicals from your water. Shop around, though — products can run anywhere from $20 for a faucet attachment to $200-plus for a complex reverse osmosis system.
Tap Out? Wonder how your tap water measures up? Go to ewg.org and enter your ZIP code to get a report on the possible contaminants in your water.
Alkaline water is still having a moment, with proponents on both sides arguing its veracity. However, there are some studies of late that support the use of alkaline water by athletes: When you exercise, your muscles produce more hydrogen ions than you can effectively remove, increasing internal acidity and inciting fatigue. Drinking alkaline water — which has a pH greater than 7 — can enhance your body’s buffering capacity, assuaging acidity and improving performance, according to research published in the Journal of the International Society of Sports Nutrition. Other studies suggest that alkaline water could improve overall hydration by helping you retain electrolytes. Research aside, drinking alkaline water won’t do you any serious harm; it may cause some stomach upset if you’re not used to it and it’s pricy, but other than that, bottoms up.
$$ Saver: Go alkaline on the cheap by mixing 8 ounces of distilled water with 1/8 tablespoon of baking soda. There are more complex — and tastier — recipes available,
so search online for more options.
Electrolytes are electrically charged particles such as potassium, sodium, magnesium, calcium and phosphate. The electrical charges of these particles stimulate your muscles and nerves to contract and help regulate the fluid balance in your body by helping your body absorb water more quickly. When you sweat you lose electrolytes, and if you don’t replenish them, you could experience muscle spasms or cramping, fatigue, nausea and mental confusion. You’ll also feel weaker and unmotivated in subsequent workouts. Traditional sports drinks contain lots of electrolytes, but they also contain large amounts of sugar — which is great if you’re running a marathon but not so much if you’re doing a Tabata. Instead, try a calorie-free water infused with electrolytes, such as Propel, or add an electrolyte tablet to your water, such as Nuun, which has only 10 calories per tab ($7, 1 tube — 10 tabs, nuunlife.com).
$$ Saver Make your own electrolyte water by mixing ½ teaspoon of baking soda, 2 tablespoons of agave nectar (or sugar) and ½ tablespoon of sea salt in 1 quart of water.
Coconut water naturally contains electrolytes like sodium and potassium (40/600 milligrams per cup, respectively), and it acts much in the same way as an electrolyte water or tablet. Because it is lower in calories, it’s a better hydration choice than a sports drink for shorter workouts and, according to research, was shown to cause less nausea and stomach upset than a regular electrolyte drink when ingested postworkout. However, research has also concluded that coconut water is no more hydrating than a sports drink and replenishes electrolytes no better than a potato — and is way pricier than either. It is tasty, however, and if it will make you drink more liquids, then have at it.
This is the newest of the trends, and all the Hollywood stars have been seen around Beverly Hills toting it. Proponents claim that adding hydrogen gas to plain water leads to increased energy, improved recovery and reduced inflammation after a workout. But so far, the evidence that supports these claims is scant: A small study published in the journal Medical Gas Research done on just 10 soccer players who drank hydrogen water found that their muscles were less fatigued postworkout. There are several other small studies such as this one done on lab animals, but as of yet, there are no solid conclusions or guidelines as to how much hydrogen water you should drink in order to reap the benefits. Drinking it won’t harm you, so if you want to feel Hollywood, fab. Just be sure to purchase a brand that comes in an aluminum pouch. This is the only container that will hold the hydrogen inside. It escapes quickly from all other vessels, and by the time it gets from the factory to the store to your fridge to your mouth, you’re drinking plain ol’ water.
To stay properly hydrated, you should be drinking between 25 and 50 percent of your bodyweight in ounces every day. So if you weigh 130 pounds, you should drink 32 to 60 ounces daily.