About half your body weight is water. So if you weigh about 160-pounds (73 kilograms), you have about 80 pounds (10 gallons [36 kilograms or 38 liters]) of water in your body.
You need the right amount of water in your body for good health. Either too much or too little can cause serious problems.
The water in your body contains electrolytes. Electrolytes are minerals, such as sodium and potassium, that help with many important body functions. Your body needs the right balance of electrolytes.
Your body works to keep the amount of water and electrolytes in your blood steady
Sweating, throwing up, and having diarrhea all make you lose a lot of water and electrolytes quickly
Too little water in your body is dehydration
Too much water in your body is overhydration
When your body needs more water, your brain signals that you're thirsty
When your body has too much water, your kidneys make more urine so you pee it out
Most of the time, you can drink enough to make up for fluid you lose
How does your body balance the amount of water?
Your body constantly balances how much water and electrolytes you have.
When your body needs more water:
Your brain makes you feel thirsty so you’ll drink more
Your brain also signals your kidneys to make less urine, so water and electrolytes don't leave your body
When your body needs less water:
Your brain signals your kidneys to make more urine
What can throw off my body's water balance?
Most of the time, your body does this balancing act automatically. You don't have to think about it. It's not necessary to force yourself to drink when you're not thirsty.
However, if you lose a lot of water very quickly and don't have a way to replace it, you can have trouble. Also, certain diseases that affect your brain or your kidneys can throw off how your body balances water and electrolytes.
