H2…Oh, I Didn’t Know!

H2…Oh, I Didn’t Know!

Learn the real reasons you need water and—once and for all—how much is enough.

You don’t hear the sloshing sound of liquid when you walk, but even so, your body’s mostly water—to the tune of 60 percent. This makes daily consumption of plenty of H2O essential to your health, even more than food is. But what do you really understand about this liquid that makes up more than half of your body? Here’s what you should know.

Why do I need water? To keep your body’s functions running smoothly. Water helps nutrients cruise through your body. It’s the motor oil of your bones, lubricating your joints so they work properly. Critical electrolytes—minerals, such as sodium, potassium, and calcium, that govern our nerves and muscles—are kept in balance by the water in your body.

What happens when I’m dehydrated? Let’s start with thirst first: even before you feel thirsty, you might experience irritability, fatigue, and the inability to concentrate—which is why your first response to afternoon grumpiness should be to drink a tall glass of water. (It might ease hunger.) One sign of being chronically low on water is dry skin. Severe dehydration, though, is no joke. It affects body temperature, blood pressure, and heart rate—so always keep a bottle of water within reach on hot days.

Is it true that water helps me lose weight? Evidence suggests that this is the case: research presented at a meeting of the American Chemical Society found that dieters who consumed two 8-ounce glasses of water before meals lost an average of 5 pounds more than dieters who didn’t. Another strategy is to choose foods that are high in water content, says Jill Weisenberger, MS, RDN, CDE, author of Diabetes Weight Loss Week by Week. “Consuming water-rich foods, like fruits, vegetables, and broth-based soups at the beginning of a meal can help control overall calorie intake because they fill you up.” Try produce such as celery, spinach, zucchini, tomatoes, watermelon (surprise!), and cantaloupe—all these options contain at least 90 percent water and most provide fiber and cancer-fighting antioxidants to boot. “Even a banana is 74 percent water,” says Weisenberger.

So how much do I really need? We’re all familiar with the old eight-glasses-a-day edict. But turns out that scientific evidence doesn’t support a precise 64-ounce figure. In fact, in 2004, the Institute of Medicine came out with new general recommendations: about 90 daily ounces of water for women and 125 for men. But those numbers are simply a guideline; if you’ve exercised, you may need more fluid, for example. Even better than measuring ounces: have a look in the toilet bowl (sorry!): If your urine is dark yellow, you need more water. Clear and pale? You’re good!

Are other drinks as beneficial as water? More liquids make the list than you might think. Unless they’re alcoholic, all beverages count toward your fluid needs—even caffeinated coffee and tea, Weisenberger says. While it’s true that caffeine has a mild diuretic effect, the loss of water is small compared to the amount of fluid ingested. Drink up—to your health!