By Dr. Mercola
Your body requires water to work well. In fact, up to 60 percent of your entire body is made of water, 83 percent of your lungs is water and 73 percent of your brain and heart are composed of water. Water is very important to your ability to function, think, breathe and live.1
Your kidneys are responsible for filtering out toxins and waste products from your blood and excreting them from your body. Water carries those toxins out through your urine. Another function of your kidneys is to maintain the appropriate balance of water in your body for optimal functioning.
How Much Is Enough?
How much water your body requires will depend on several factors. The types of food you've eaten, how much you've perspired, how much dehydrating fluid you've drunk, how tall you are and how much you weigh are examples of the factors that determine how much fluid your body needs.
Your kidneys balance your body's requirement for water against the amount of water already in your body and any excess that may be present. You'll need more water on warm days when you perspire and less on days when you don't drink coffee or other caffeinated drinks.
Although you may be tempted to count the amount of coffee and soda you drink in your fluid requirements for the day, these drinks actually have a mild diuretic effect in your body. This means they may cause your body to release more urine. They are not usually strong contributors to dehydration, however.
That being said, soda is high in sugar, triggering a release of insulin and contributing to type 2 diabetes and obesity. In moderate amounts, coffee is not considered harmful to your health and may have some significant health benefits. The best fluid to use for hydration, though, is water.
Your body is your best source of information. The typical six to eight glasses of water a day may work for some people, but will not be enough for others. Instead, it's important that you learn to read the signals your body is giving you.
What You Experience
Interestingly, the first sensation you'll experience as your body needs more fluid is hunger.2,3 This is why many weight loss experts counsel their clients to drink a glass of water when they think they want to eat, and then wait 20 minutes to see if they still feel hungry.
This helps train you to recognize the differences between feeling "real" hunger and beginning to need more water. The older you get, the more likely it is that you'll start to confuse hunger with thirst. The thirst mechanism in adults becomes weaker and often is confused with feelings of hunger.
Combine that with symptoms of dehydration that can mimic feelings of being hungry, such as dizziness or feeling weak, and it's easy to see how you can get confused.
Even mild dehydration can produce an imbalance in your body's equilibrium. Dehydration is rated as mild, moderate or severe depending upon the percentage of water loss your body experiences. After losing 1 percent to 2 percent of fluid your thirst mechanism will be triggered, prompting you to drink.
At this point dehydration is already affecting your function. During mild dehydration you may have lost up to 5 percent of your body fluid. You may still be active and alert and sometimes appear to have normal body functions.4
Up to 75 percent of Americans are chronically dehydrated. Being chronically dehydrated can contribute to a long list of symptoms and medical problems that may send you to your doctor.5
Too Much of a Good Thing
You might think that you couldn't ever drink too much water, but you would be wrong. Over-hydration is an excess of water in the body, which can create an imbalance in your electrolytes. Normally your kidneys can excrete water fairly quickly.
However, when you drink a lot of water in a short period of time, you may experience some of the symptoms of too much, too soon. If you have kidney disease, you may not be able to excrete excess water as efficiently and can suffer from over-hydration.
The imbalance in sodium and potassium can result in confusion, loss of consciousness or seizures. In the early stages, you may appear to be drunk from the lack of electrolyte balance in your brain.6
Although rare, the drop in sodium levels, called hyponatremia, is called water intoxication. The problem occurs when you drink a surplus of fluid without giving your kidneys time to excrete the excess.
Your kidneys can filter and excrete approximately one-half liter (approximately 16 ounces) each hour. When you out drink your kidneys, you can get into trouble.7
Symptoms of Dehydration
✓ Dry or sticky mouth
✓ Dry, cool skin
✓ Reduction in physical/athletic performance10
✓ Reduction in cognitive performance11
✓ Impaired heart function
✓ Difficulty concentrating
✓ Increased tension and anxiety
✓ Low urine output
✓ Weight gain
Symptoms of long-term dehydration or more severe dehydration include:
✓ Increased cholesterol levels
✓ Premature aging
✓ Rapid breathing
✓ Rapid heartrate
✓ Sunken eyes
✓ Unconscious or delirious
✓ Low or no urine output
✓ Low blood pressure
Read the Signs in Your Urine
You may avoid the effects of dehydration or chronic dehydration when you pay attention to the signs your body is giving you. The character and color of your urine is one of the earliest signals you'll have of your hydration status.
By paying close attention each day, you may be able to prevent experiencing the effects of dehydration.
The amount of urine and the number of times you urinate each day are indicators of your hydration status. Most people urinate between four and seven times each day, depending upon the size of your bladder and the amount of urine you have to release.12
This means there is no precise number of times you'll urinate every day. Specific foods and fluids can also irritate your bladder, causing you to urinate more frequently.
Although you are going to the bathroom more, you aren't releasing more urine because your kidneys aren't producing an excess of urine. Instead, your bladder is irritated and you feel the urge to go more frequently. These foods and fluids include:
✓ Caffeinated beverages
✓ Citrus fruits
✓ Carbonated fluids
✓ Tomato-based products
When you feel the urge to go, it's time to head to the bathroom. Delaying a trip to the bathroom may cause your bladder to become over-distended. Like most common elastic properties, once your bladder has been stretched too many times, it won't return to a normal size, but rather will stay distended. Distension can cause nerve and muscle damage, leading to further bladder damage and urinary tract infections.13
Color is the easiest way to determine if you are drinking too little or too much fluid throughout the day. The color of your urine is determined by the concentration of waste products in the fluid. The more water you have in your body for your kidneys to mix with waste products, the lighter in color your urine will be.
You should be drinking enough water for your urine to be a light straw color, or light yellow. If your urine is darker, then your kidneys are working harder to concentrate the waste products and remove them from your body without causing further dehydration.
You may not be aware of some of the physical and cognitive reductions in your performance, but they are there. Don't rely on your perception of thirst to determine if you need fluid, but rather on the color of your urine. If your urine is almost clear you may be drinking too much.
Your urine should be relatively odorless. The scent will depend upon your level of dehydration, the foods you've eaten in the last 24 hours and whether or not you have a bladder infection. The more concentrated your urine from waste products eliminated by your kidneys, the stronger your urine will smell of ammonia.14
Some medications and urinary tract infections will also change the color and odor of your urine. If you have an infection, your urine may appear cloudy and can be blood tinged. An abnormally sweet odor from your urine may indicate that you have a high level of glucose in your urine from uncontrolled diabetes. Other conditions that affect the odor of your urine are liver failure and high levels of ketones in the urine.15
Type 2 diabetes is also called diabetes mellitus. The word mellitus in Latin means "honey." Up until the 11th century doctors diagnosed diabetes mellitus based on the sweet taste of the patient's urine. "Water tasters" were hired to distinguish the difference between normal urine and urine from individuals with uncontrolled diabetes.16
Thankfully this practice is no longer required. And, while the idea of drinking urine is distasteful, highly concentrated urine you produce when dehydrated will have a far stronger taste than urine produced when you are fully hydrated.
Can You Train Your Bladder?
If you don't have any underlying medical conditions affecting your kidneys or bladder, then it may be possible to train yourself to urinate only when the urge is strong. There is a line between going every time you feel an urge and waiting until it's painful to hold the urine any longer.
You don't want to over-distend your bladder (so don't wait until you feel pain), but you don't have to go every time your bladder has a few drops of urine. Remember, your kidneys are making urine all the time. The urine is flowing out of your kidneys and into your bladder as it is being produced. Realistically, if you are hydrated, you could go to the bathroom every 30 minutes and have something to pee.
But since most people don't want to go every 30 minutes, you usually wait until you feel an urge. The trick is to delay going to the bathroom until the urge is strong but not waiting too long. You gradually become more sensitive to the signals your bladder is sending to your brain so you overlook the little urges and pay attention as they get stronger.17
If getting up in the middle of the night to urinate is interrupting your sleep pattern, it may be time to limit your fluid intake after 6 p.m. This gives your kidneys enough time to filter the excess water so you can sleep through the night. Remember to drink 16 ounces of water first thing in the morning to start hydrating your body once again.