The human body is composed mostly of water and loses a bit of that water every moment through breathing, sweating, urinating, and almost every other movement you can make. Replenishing by drinking a sufficient amount of water helps the body to regulate its temperature, maintain a healthy metabolism, engage in proper digestion, avoid constipation, flush waste products, reduce excess hunger, and fulfill other important functions. While drinking the right amount of water is necessary to maintain a properly functioning and healthy body, drinking too much can be just as dangerous as drinking too little.
Overhydration and Hyponatremia
Unfortunately, there really can be too much of a good thing. In fact, several people have actually died from drinking too much water. Instances of death by water intoxication (hyponatremia), where the sodium concentration level of the blood is reduced to significantly below normal, include a contestant in a radio station’s water drinking contest, a fraternity-hazing participant, and several endurance athletes.
The symptoms include nausea, vomiting, fatigue, muscle weakness or spasms, frequent urination, dizziness, headache, and mental confusion. If the case is severe enough, water may enter brain cells, leading to delirium, seizures, coma, respiratory arrest, brain stem herniation, and even death.
The Underlying Physiologic Process
A healthy body naturally seeks its own perfect fluid balance. When you work out and lose fluid through sweat, your body responds with a feeling of thirst.
If you drink more than you need, your body responds by urinating. Healthy kidneys can excrete about a quarter of a gallon of water every hour. That rate of excretion may be reduced by a health condition or it may be lower in a stressful situation, such as a marathon run, when your brain sends out signals for your body to retain fluids to meet the demands being placed on it. In this case, drinking a quarter of a gallon per hour may result in a net gain of water.
If you drink so much water that your body can’t easily dispose of the excess, your blood sodium concentration level will decrease. In an effort to equalize sodium levels in your body, water will be drawn out of the blood and into the body’s cells, making the cells swell. While most cells are embedded in flexible tissues and have a little room in which to swell, brain cells are tightly packaged inside the skull where there is no room to swell. Consequently, swelling in the brain is very serious and requires immediate treatment.
How Much Is Just Enough?
The old rule used to be to drink eight, 8-ounce glasses of water a day, but experts are now telling us that it may even be dangerous to drink that much. They say that the correct amount depends on your weight, activity level, and environment. It is usually a good idea to drink, every day, between half an ounce to one ounce of water for each pound that you weigh. So, if you weigh 150 pounds, you should drink between 75 to 150 ounces of water every day.
If you exercise frequently and live in a hot climate, you should drink on the high end of that range. The longer and more intensely you exercise, and the more you sweat, the more you should increase your water intake. Of course, because sodium is lost through perspiration, you might want to consider drinking a beverage that is designed to provide sodium replenishment.
The amount of water you need is also influenced by other factors that affect your excretion of water, such as a stomach virus or nursing a baby. If you’re not sure whether you’re drinking the right amount, it’s a good idea to check the color of your urine. If it is completely clear, you may be drinking too much. On the other hand, if your urine is a lighter shade of yellow, you are probably well hydrated but safe.
Listen To Your Body
It’s true: Your body talks. At least it does when it comes to such things as whether or not you should be drinking more water. You just have to learn how to listen to it.
Last year, a panel of 17 international experts collaborated on new guidelines for the safest way to gauge how much water to drink. They determined that using your thirst mechanism to guide fluid consumption should limit the possibility of excess drinking while providing you with enough fluid to prevent dehydration. So, in most situations, the response to how much you should drink may be best answered by simply deciding whether you are thirsty!