From VOA Learning English, this is the Health & Lifestyle report.

Drinking enough water is important to our health. If we want to operate at our highest level and feel great both mentally and physically, we need to stay hydrated throughout the day.

But often ... we don't.

People may go through their days dehydrated and not even know it.

Dehydration can make you sick. Extreme dehydration can lead to death.

However, many side effects of dehydration are not life-threatening. But they can still affect your health. In fact, you may be suffering from some of these side effects without knowing that dehydration is the cause.

First: What is dehydration?

Dehydration happens when you use or lose more fluid than you take in. Your body doesn't have enough water and other fluids to carry out its normal functions.

On the U.S. Geological Survey Water Science School website, experts explain how much of our bodies are made of water.

Jeffrey Utz is a doctor of neuroscience and children's medicine at Allegheny University in Pennsylvania. He writes that different bodies have different amounts of water in them. And that amount changes throughout our lives.

Babies have the highest percentage of water in their bodies. When we are born our bodies are about 78 percent water. By the time we turn one year old, that amount drops to about 65 percent.

Adult men are about 60 percent water, while adult women are about 55 percent.

Your body type matters, too.

The amount of muscle or fat you have affects the percentage of water in your body. People with more fatty tissue have less water than people with less fatty tissue.

Now, let's talk about how dehydration affects the body. Experts on the website Health.com explain the signs of dehydration.

Here are the top five:

You have bad breath and bad skin

Bad breath is a sign that the mouth does not have enough saliva. This increases bacteria and results in bad breath.

And for healthy skin, it is important to drink a lot of water. Skin doctors warn that skin creams only do so much. The best way to hydrate your skin is from the inside out.

You feel tired

If you feel tired during the day, your body may be telling you to drink some water. One doctor on Health.com explains that, when you are dehydrated, your blood pressure drops, your heart rate increases and blood flow to the brain slows. These can all make you feel tired. This doctor adds that when your muscles don't get enough water, physical work can be more difficult and tiring.

Your workout could be affected.

Our bodies often do not know the difference between hunger and thirst. One of the experts on Health.com advises high-level athletes on kinds of foods to eat. That expert is Amy Goodson. She explains that when you exercise while dehydrated, your body uses stored carbohydrates faster than if you were fully hydrated. She adds that once you finish exercising, your body will want those carbohydrates back. This, she warns, may lead to overeating.

Your brain works poorly

When our bodies do not get enough water, blood flow to the brain slows. This can cause several problems. You may get in a bad mood. Every little thing gets on your nerves, or angers you. You may have a difficult time focusing. You may not be able to think clearly about a problem. Dehydration can also cause headaches.

You suffer from muscle cramps

When your body does not get enough water, it sends out an emergency signal to protect the most important organs. So, the body sends the fluids in the body away from non-important parts of the body like the muscles. This can lead to painful muscle cramps.

Okay. So, how much water do you need?

The amount of water you need to stay hydrated depends on many conditions.

On average, an adult male needs about 3 liters of water every day. An adult female needs to get about 2.2 liters of water every day. Keep in mind, this doesn't have to come only from drinking. We also get water from the foods we eat, especially from fruits and some vegetables.

However, some people need to drink more than others.

Those who exercise every day should drink more water. Anyone who drinks a lot caffeine or alcohol in a day should drink extra water, as well.

If you are recovering from a sickness, you should drink more water than usual. And if you work outside or in hot conditions, make sure you drink enough water.

And that's the Health & Lifestyle Report.

I'm Anna Matteo ...

and I'm Bryan Lynn.

Anna Matteo wrote this story for VOA Learning English. Ashley Thompson was the editor.

_______________________________________________________________

hydrated – v. to supply (something) with water ­– adj. to drink enough water : Remember to stay hydrated.

dehydrated – v. to lose too much water

saliva – n. the liquid produced in your mouth that keeps your mouth moist and makes it easier to swallow food

thirst – n. an uncomfortable feeling that is caused by the need for something to drink

athlete – n. a person who is trained in or good at sports, games, or exercises that require physical skill and strength

carbohydrate – n. any one of various substances found in certain foods (such as bread, rice, and potatoes) that provide your body with heat and energy and are made of carbon, hydrogen, and oxygen

mood – n. the way someone feels : a person's emotional state

focus – v. to direct your attention or effort at something specific

fluid – n. capable of flowing freely like water

muscle cramp – medical noun A muscle cramp is a strong, painful contraction or tightening of a muscle that comes on suddenly and lasts from a few seconds to several minutes. It often occurs in the legs.