Water, Water, Water: How Much Do I Really Need?

You have probably heard many opinions as to how much water you need to be drinking. You need 8  8 oz. glasses a day, drink a gallon of water a day, drink 3 liters of water a day, coffee will dehydrate you and so on. I have heard them all and see many trainers, coaches, and well-meaning self-proclaimed experts giving their opinions all over Facebook and blogs. After a review of several articles from a registered dietitian (Martha McKittrick), a licensed nutritionist (Monica Reinagel), NASM, and the Mayo Clinic, I have some good information and suggestions to share with you.

Some Facts

  • About 60% of your body weight is water.
  • Adequate water intake helps to prevent water retention.
  • You lose about 2-2 ½ liters (about 64-80 oz.) of water a day through breathing, perspiring, urinating, and bowel movements.
  • Your thirst reflex does decline with age.
  • Food contains about 20%-25% of the water you need daily, depending on your diet.
  • Sufficient water intake aids on body-temperature regulation.
  • Liver function improves with adequate water intake, increasing the percentage of fat used for energy.
  • Adequate water intake can come from a variety of fluids, not just water (although most should come from water).

Some Interesting Information

So how do you know if you are getting enough water? The signs of inadequate fluid consumption are as follows:  headaches, dry mouth, feel light-headed, difficulty concentrating, fatigue, little urination or dark-colored urine, and constipation. The effects of dehydration on your body are significant. You will have decreased blood volume, decreased performance, water retention, sodium retention, decreased blood flow to the skin, increased heart rate, and you feel like you are working harder than you are. Mild dehydration occurs when you lose 3%-5% of your body weight through loss of fluids.

The Institute of Medicine determined that the adequate intake of fluid for men is about 3 liters a day (about 96 oz.) and for women is 2.2 liters (72 oz.) a day.

The Institute of Medicine determined that the adequate intake of fluid for men is about 3 liters a day (about 96 oz.) and for women is 2.2 liters (72 oz.) a day. This is a great starting number but you need to adjust for many factor. More fluid is needed during exercise. According to the NASM personal fitness training text, a good rule of thumb is 20-40 oz. of extra fluid for every hour of exercise. If you live in a hot or humid environment, you need more fluids due to increased sweating. You also need more fluids at altitudes greater than 8,000 feet. You require more fluids when ill with vomiting and/or diarrhea or if you are pregnant or nursing.

What about caffeinated drinks such as coffee and tea? I know I have always heard that these drinks will dehydrate you. What I have learned is that this is simply not true. Studies have shown that if you regularly drink these beverages, they will not dehydrate you and will positively contribute to your overall fluid intake. If you do not regularly drink caffeinated drinks, a cup of coffee will offer you about the equivalent to 2/3 of a cup of water. You will simply be getting your fluid less efficiently.

It is possible to be over-hydrated. There is a condition known as hyponatremia, which is characterized by low sodium blood levels. This happens when your kidneys are unable to excrete the excess water. Those most at risk are endurance athletes, people with kidney disease, or the elderly who take multiple medications that can inhibit the body’s ability to excrete waste properly. In general, the average American is not at risk for this condition.

Bottom line, listen to your body, evaluate your environment, activity level, and diet to make an educated determination as to how much water you need to consume to stay well hydrated.

On a Personal Note

Let me say, the nutrition coach I worked with (Ruben Sandoval with Fit To Be In Your Kitchen) suggested I drink 100 oz. of water a day. I have noticed several positive benefits to this advise including: no edema, improved appearance of my skin, regular bowel movements, reduced hunger, and efficient errand running due to the constant need to know where the nearest public bathroom is!

Now, go refill your water bottle and enjoy the benefits of being well hydrated!

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One Response to Water, Water, Water: How Much Do I Really Need?

  1. Shauna July 22, 2013 at 8:11 am #

    Thank you Nancy ~ this is a great help!! I now know what I need to do!

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