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Experts explain why you don’t need 8 glasses of water a day

Last updated on January 27, 2018

You’re probably one of the millions still confused about how much water is enough water as a daily minimum. There are numerous conflicting suggestions that range from eight glasses of water a day to several liters, neither of which are technically correct.

The original suggestion of drinking at least eight cups of water each day is a standard set from the 1940s when the National Academy of Sciences published an article that suggested the average person consume one milliliter of fluid for each calorie burned. Someone with a daily intake of 2,000 calories, for example, would then require just over eight cups of fluids per day.

The National Academy of Sciences set an original standard of eight cups per day, not eight glasses. The difference is one cup is equal to eight fluid ounces, while the average household drinking glass starts at eight ounces and goes up to 16 ounces. When someone suggests drinking eight glasses of water per day, there is a sudden discrepancy.

Even though there was a set measurement in place, word-of-mouth changed the standard from cups to glasses then to liters that eventually included water bottles of no set size. Unfortunately, this inaccurate dictum caught on and continues to confuse consumers.

Another misconception is that it must be water. While water certainly is the healthiest choice, the body requires fluids every day.

Fluids include all liquids you drink as well as liquids derived from foods eaten. Fluids do not mean only water. The average adult gets approximately 20 percent of their daily fluid intake through the foods they eat. Think leafy greens, oranges, tomatoes, melons and celery, which contain high amounts of water. Other foods such as fish (flounder is 79 percent water), chicken (69 percent water), eggs (63 percent water) and of course soup, all contribute to your daily fluid intake.

Factors that influence your daily fluid intake
Where you live: If you sweat often due to a hot or humid climate, you’ll need to replace this lost water with additional fluids. Hot or humid climates, as well as heated indoor air, cause water loss through the skin. Even living in high-altitude places can cause frequent urination and an increase in breathing, which can use more body fluids.

Being sick: When you’re sick vomiting, experiencing diarrhea or have a fever, your body loses more fluids than normal. When you’re sick, water is the best fluid replacement option unless your doctors suggests otherwise. Health conditions such as urinary tract stones or a bladder infection will also require an additional intake of water.

Exercise: Physical activity that causes you to sweat will require additional fluids to compensate for the loss. For non-intense exercise (exercise that lasts less than one hour) you should consume an additional 1.5 to two cups of water. For intense exercise that lasts longer than one hour, you will want to compensate with additional fluids. The amount of fluids you’ll need is directly related to how much you sweat. Fluids lost from long bouts of intense exercise should be replaced with a sports drink that contains sodium.

Being pregnant: The Institute of Medicine recommends pregnant women consume 10 cups of fluids per day. That’s about 2.5 liters, however, women who are breastfeeding should drink at least 13 cups or about three liters of fluids each day.

Caffeine consumption: Caffeine encourages urination, which is not necessarily a bad thing unless you’re a heavy caffeine consumer. Remember caffeine is not only found in coffee. It is also found in concentrated amounts in teas, sodas and chocolate. People who consume large amounts of caffeine generally go through their fluid intake faster than people who consume moderate amounts, which requires additional fluid replacement with non-caffeine fluids.

How much water should I drink in a day?
The Institute of Medicine recommends women consume 91 ounces or about 2.7 liters of fluids per day, while it’s suggested men consume 125 ounces or about 3.7 liters of fluids each day. This base amount of suggested fluid intake will vary on personal factors.

Tips for proper hydration

  • Cold water is the best choice for rehydration as the body absorbs it faster than warm water.
  • If you’re not into water, fluids such as juice and milk are mostly water.
  • Drink juice or water with each meal and in between meals.
  • Make sure to drink water before, during and after you exercise.
  • People suffering incontinence should limit their fluid intake to between six and eight cups of fluids (from all sources) per day. They should also not drink more than eight ounces of fluids at one time, however, if you are thirsty from heat or exercise, drink water.
  • Thirst is a sign your body is becoming dehydrated. Drinking small to moderate amounts of water repeatedly is the best way to treat dehydration.
  • If you generate about 6.3 cups or 1.5 liters of light yellow or colorless urine each day, you’re likely getting enough fluids.

Are people really that dehydrated?
A survey by the International Bottled Water Association in combination with Rockerfeller University studied 2,818 adults across 14 U.S. cities and found on average, adults were drinking about six cups of water each day on top of other fluids, which included tea, coffee, juice, milk, sports drinks and alcoholic beverages. When combined, the study concluded the average adult consumed 17.6 cups of fluids each day, which is enough to have you urinating every waking hour.


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