What’s the deal with water?

By Judy Torel

“Drink a minimum of eight eight-ounce glasses of water a day for health and to avoid dehydration.”
You have heard and read this hundreds of times by now and if you are not slavishly trying to force yourself to consume this amount, then you are guilt-ridden for not being a good water drinker!
What does water do in your body? Is there a general rule for daily water consumption? And where did this guideline come from anyway?

What does water do in your body?
The average woman’s body is comprised of 45-60% water. The average man is 50-65%. Our lungs are composed of 90% water and our blood is 80%. Water serves as a solvent for nutrients and delivers nutrients to cells as well as helps eliminate waste products from the cells. Both the spaces between cells (intercellular spaces) and the spaces inside cells (intracellular spaces) are filled with water. Every metabolic process in your body is dependent on water.
There are several factors that influence how much water a body needs in a day:
Exercise: The more you exercise, the more water you need to replace what you lose in sweat and to maintain proper metabolic functions necessary to continue exercising.
Environment: A hot or humid climate, a dry heated dwelling in the winter and altitudes above 2,500 feet all place higher water demands on a human body.
Health: Vomiting, diarrhea and fever result in loss of water from the body. Various health conditions like bladder infections and urinary tract stones require higher consumption of water. Pregnancy and breastfeeding also place higher hydration needs on a woman’s body.
Every day a human body loses water through breathing, perspiration, urination and bowel movements. So, even the most sedentary person needs to replace water on a daily basis.

Where did the 8×8 recommendation originate?
This guideline originated from a statement issued by the Food and Nutrition Board of the National Research Council, which stated that one milliliter of water for each calorie of food is the recommended hydration formula. An average intake of 2,000 calories per day would result in a hydration intake of 2 liters or 64 ounces of water per day (8×8 ounces). However, the Board also stated that most of this water is contained in prepared foods, but that was omitted or missed, so the recommendation was interpreted as how much water to drink each day.
But there are other ways that humans get hydration on a daily basis. Many of the foods we eat are made up of at least 20% water, with fruits and vegetables containing up to 90% water!
Beverages such as beer, wine and caffeinated drinks such as coffee, tea and soda all contribute to hydration despite the popular misconception that they lead to dehydration. Current research shows that caffeinated beverages do not result in a lower hydration level partly because the caffeine is taken into the body in a liquid medium. Water is one of the best hydration replacements because it is calorie-free and readily available, but it is not the only source of hydration.

If you are an athlete who is exercising over 60 minutes at a time, an electrolyte replacement sports drink such as Gatorade 2 will not only replace hydration, but will also keep a proper balance of sodium, magnesium, calcium and potassium, otherwise known as the electrolytes.

Electrolytes are necessary for proper functioning of the body. They keep the heart pumping and nervous system operating. If an athlete over drinks water without replacing electrolytes, a condition called hyponatremia can result. This is when sodium levels become too distilled by too much water and it can result in death.
Recently the USATF (United States Track and Field Association) has revised its’ guidelines for hydration during running events. Before the recommendation was to drink before you are thirsty, the new recommendation is that you drink when thirsty during a race. The rule of thumb is to consume 4-12 ounces of liquid per 15 minutes of exercise. This amount varies depending on individual sweat rate, environmental conditions and conditioning.

Is there a general rule for daily hydration?
There are a couple of methods for determining hydration replacement for an average adult living in a temperate climate. The first is the replacement approach. Science has shown that the average urine output for an adult is 1.5 liters per day. We lose an additional liter through breathing, sweating and elimination. That means 2.5 liters a day needs to be replaced. We generally take in 20% of that amount from the foods we eat. That leaves about 70 ounces to be replaced by what we drink. So 8×8 ounces is not that far off.
The second approach is the dietary replacement approach. The Institute of Medicine recommends that men consume 3 liters (about 96 ounces) and women consume 2.2 liters (about 70 ounces).

There is also evidence to indicate that the average person really doesn’t have to worry about a specific formula for daily hydration. Published surveys document that the mean daily fluid intake of thousands of healthy humans is less than 8×8 ounces per day. This places the burden of proof back on the advocates for specific formulas for fluid replacement. (This does not apply to the formulas utilized for athletes where there is scientific evidence supporting fluid and electrolyte replacement strategies.)

Bottom line: On a daily basis, follow your thirst, eat foods that are healthy and contain a high water content and let go of any guilt for not following a specific hydration schedule!

Judy Torel is a therapist/personal trainer with a Master’s degree in psychology. She is certified through the American College of Sports Medicine as a fitness trainer and works out of Planet Fitness and Deb's Sweat Shop Extension. She can be reached at JTOREL2263@yahoo.com