Healthy Living: Your Most Important Nutrient 💦

Did you know you’re made of mostly water?

It’s true!

In fact, by weight, your body - as a whole - is approximately 67% water. 

Moreover, your blood is mostly water. So are your brain, heart and lungs. Your muscles contain more than 70% water and your skin contains over 60% water.

But exact percentages will vary for each individual. For example, men have more total body water than women. Age is also a factor. Children have a greater total body water percentage than adults. When you’re more active, you’ll lose more water too. With rising temperatures, you’ll lose more water. Sweating causes water loss. Breathing causes water loss. You even give up water for your personal waste system, via your kidneys and your gut.

But your body doesn’t make water. When your body needs a resource it doesn’t make, the resource is called “essential.” Therefore, water is essential. You have to drink water to survive. 

Believe it or not - water is more vital than food. Have you ever heard of the wilderness survival rules of 3? These rules basically tell you what to prioritize if you’re stuck in the wild. 

The Wilderness Survival Rules of 3:

  • You can survive for 3 minutes without air (oxygen).
  • You can survive for 3 hours without shelter in a harsh environment (unless in icy water).
  • You can survive for 3 days without water (if sheltered from a harsh environment).
  • You can survive for 3 weeks without food (if you have water and shelter).

So, now that you know you need to drink water to survive, how much water should you drink?

First, you should know approximately 75% of Americans are chronically dehydrated. So, your friend likely can’t advise you well about hydration.

While the classic recommendation is to drink eight 8 ounce glasses of water each day, I have to respectfully disagree. Here’s why:

In a lab, we can actually calculate the right amount of water for you. We’d measure your height, weight, perspiration, urine output, and physical activity. And we’d have to consider your sex and climate.

Given these considerations, this equation gives the minimum amount of water you need each day:

1500 mL + [weight (kg) x 20 ml/kg/day]

In medicine, we often use the 70 kilogram (kg) person as an example. (You can convert pounds to kilograms by dividing by 2.2.)

Using this equation, we determine that a 70 kg person needs to drink at least 1640 mL of water each day. But that’s just enough to survive. But how much water do you need to thrive? More, right?

Research shows women who are well-hydrated drink an average of 2.7 liters (91 ounces) per day. Well-hydrated men drink 3.7 liters (125 ounces) per day. 

So, make your goal 3 liters (or 11 glasses) of water per day. 

Hydration is the unsung hero of wellness. Think of water as your most important nutrient, and drink up, my friend! 

by Brittny Howell, MD


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