Do You Really Need 8 Glasses of Water a Day?
Nutrition Nov 16, 2016
Do You Really Need 8 Glasses of Water a Day?

You’ve heard the advice many times. Maybe you’ve even tried to follow it. Drink 8 glasses of water a day. If so, and you failed to keep it up for more than a few days, there might be a biological reason for that.

A recent study verifies that your body actively resists drinking more water than you need. Drink when you’re thirsty and crave it. When it starts to feel like a chore, stop.

It’s All About The Balance

We need a healthy balance of all nutrients, including water. Drink too little, and you can become dehydrated. However, that doesn’t mean it’s healthy to force yourself to drink water when you’re not thirsty. You’re then overriding a swallowing inhibition.

Be Aware Of The Dangers Of Dehydration

Dehydration can lead to many health issues. According to the Mayo Clinic, water:

  • Makes up 60% of body weight
  • Washes toxins out of tissues
  • Carries nutrients into body cells

When you don’t get enough, that can cause serious medical problems. To that list, WebMD adds kidney stones.

As with anything in life, it’s all about moderation and listening to what your body needs.

How Much Water Do You Actually Need?

There’s no set formula. The Mayo Clinic lists factors that affect how much you should drink. You need to replace the water you lose, especially through sweating, so athletes and people in labor intensive jobs such as construction workers need more fluid than an office worker in an air-conditioned building.

Where Did This Myth Come From?

According to this article published in the American Journal of Physiology, it may have come from a 1945 article of the Food and Nutrition Board of the National Research Council, which says people need 2.5 liters of water on average.

However, the article omits the full context in which it states most of the recommended 2.5 litres can come from the daily food consumed. As the Mayo Clinic article suggests, the 8 eight-ounce glasses of water a day myth, or 8 by 8, seems to hang on just because it’s easy to remember.

What Happens When You Drink Too Much Water?

When you drink more water than your kidneys can excrete, that dilutes the electrolyte balance of your blood, and can dangerously lead to low levels of sodium, a condition known as hyponatremia. The excess water enters your cells, causing them to swell. Hyponatremia, often called water intoxication, can lead to lethargy, and if severe enough, can be fatal.

A new study from Monash University revealed scientists recently used fMRI scans to study people drinking water. When thirsty after exercise, they easily swallowed water. However, when forcing themselves to drink, that activated a swallowing inhibition. The authors of the study believe that is the body’s regulatory mechanism acting to prevent hyponatremia.

Healthy Hydration

In 2004, the National Academies of Science advised men to consume a total of 3.7 liters of water daily, and women 2.7 liters. That’s actually more than 8 eight-ounce glasses a day. However, they recommend that as the total consumption, counting the water in the food you eat and other beverages you drink. It doesn’t mean you have to drink it all as pure water. And those guidelines are for sedentary people living in a temperate climate.

Also according to this paper, beverages containing caffeine do count. Although caffeine is a diuretic, causing people to urinate, the effect is temporary. No evidence indicates caffeine leads to less water within the body.

Now that you have the full facts, don’t fall for common health myths. Drink when you’re thirsty. Don’t force yourself to gulp down more water than you really need.