A common refrain we hear is that the key to staying hydrated is drinking eight glasses of water a day. While this is a good barometer, the easiest way to know how much to drink is to simply obey your thirst. Drink when your body tells you it’s thirsty.

Don’t wait—by the time you feel parched, you have already lost 1 to 2 percent of your body’s water.

There are a few ways you can judge whether you’re hydrated enough. If your urine is clear or pale yellow, you’re set. You can also measure it by drinking as much water as it takes to keep your lips and mouth moist throughout the day.

If you’re tired, you may be dehydrated. One hidden cause of fatigue is mild dehydration. Just a little deficit can make you feel drained. If you’re feeling somewhat low on energy, a glass of water (instead of a bag of M&M’s) may be the jolt you actually need.

Also, remember to sip—not gulp—to get what your body craves. In one study from the University of Toronto, people who downed a glass

of water in 15 minutes quickly eliminated most of it the next time they hit the bathroom. But those who slowly sipped held on to much more.

In addition to drinking, you can munch, crunch and spoon up water-rich foods. Instead of just drinking water, think about how you can fit fruit, veggies and dairy products into your diet, too. Most healthy foods are also a great source of additional fluids and provide about 20 percent of your daily water needs. Try these water-rich foods:

One added benefit of staying hydrated is weight loss. In a University of Illinois study, people who drank one, two or three extra glasses of water a day took in between 68 and 205 fewer calories and cut their intake of salt and sugar. Also, two Virginia Tech studies showed that drinking water before meals cut calorie intake by 13 percent and helped middle-aged men and women lose more weight than those who didn’t drink water before their meals.

Drink up!