Water is your body's principal chemical component and makes up about 60 percent of your body weight. Every system in your body depends on water. For example, water flushes toxins out of vital organs, carries nutrients to your cells and provides a moist environment for ear, nose and throat tissues.
Lack of water can lead to dehydration, a condition that occurs when you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired. Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water. It's generally not a good idea to use thirst alone as a guide for when to drink. By the time you become thirsty, you may already be slightly dehydrated. As we age, the body is less able to sense dehydration and send your brain signals of thirst. On the other hand, excessive thirst and increased urination can be signs of a more serious medical condition. Talk to your doctor if you experience either.
How much water should you drink each day? It's a simple question with no easy answers. Research has provided varying recommendations over the years. Fluid needs are based on the individual and depend on many factors such as where you live (hot needs more water), activity level, age, your health condition and your body weight.
The average adult loses about 10 cups of water on a typical day. Most people need roughly 8 to 12 cups of fluid a day, which we obtain from both food and beverages. If you drink enough fluid so that you rarely feel thirsty and produce 1.5 liters (6.3 cups) or more of colorless or slightly yellow urine a day, your fluid intake is probably adequate.
One method that might be helpful in providing an estimate of a person’s fluid needs:
25 to 30 ml per kilogram of body weight = fluid need
250 pounds (114 kg) 114 x 25 - 30 = 2850 to 3409 ml = 95 to 113 ounces
(6 to 7 bottles of water)
400 pounds (181 kg) x 25 – 30 = 4525 to 5430 ml = 151 to 181 ounces
(9 to 11 bottles of water) *30 mls = 1 ounce*
Another method to calculate water needed:
Weight in pounds divided by 2 = amount of fluid in ounces
250 pounds divided by 2 = 125 ounces
Reasons you will need to increase your fluid intake…
Exercise - If you exercise or engage in any activity that makes you sweat, you need to drink extra water to compensate for the fluid loss. An extra 14 to 20 ounces of water should suffice for short bouts of exercise, but intense exercise lasting more than an hour (for example, running a marathon) requires more fluid intake.
Environment - Hot or humid weather can make you sweat and requires additional intake of fluid. Heated indoor air also can cause your skin to lose moisture during wintertime. Altitudes greater than 8,200 feet (2,500 meters) may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.
Illnesses or health conditions - When you have fever, vomiting or diarrhea, your body loses additional fluids. In these cases, you should drink more water. Also, you may need increased fluid intake if you develop or are prone to certain conditions, including bladder infections or urinary tract stones. On the other hand, some conditions such as heart failure and some types of kidney, liver and adrenal diseases may impair excretion of water and even require that you limit your fluid intake.
Breast-feeding - Women who are breast-feeding need additional fluids to stay hydrated. Large amounts of fluid are used especially when nursing. The Institute of Medicine recommends that women who breast-feed consume 3.1 liters (about 13 cups) of fluids a day.
Dehydration is much more common than over hydration. Consuming too much water can have an adverse effect on the body, but is a relatively rare occurrence. Although uncommon, it is possible to drink too much water. When your kidneys are unable to excrete the excess water, the electrolyte (mineral) content of the blood is diluted, resulting in low sodium levels in the blood, a condition called hyponatremia.
Endurance athletes, such as marathon runners, who drink large amounts of water, are at higher risk of hyponatremia. In general, though, drinking too much water is rare in healthy adults who eat an average American diet. An adult whose heart, kidneys, and pituitary gland are functioning properly would have to drink more than two gallons of water a day to develop water intoxication. Eating a salty food would negate the result.
It’s important to be well hydrated and remember plain water is the best source!