Hydration Basics

We all know that we need to be drinking water every single day. And let’s be honest, how many times do we hear things like “drink more water!” and “you need to be staying hydrated!” It is easier said than done. But, the real question is why is hydration so important? 

To begin, the human body is made up on average of 60% water, but this can range from 45-75% depending on age, gender, and body composition. In addition to this, vital organs such as the brain and heart are composed of 73% water, and the lungs are composed of 83% water. 

When it comes to athletes, proper hydration is vital to performance, injury prevention and recovery. If dehydration occurs during a practice or competition, it can result in cramping, dizziness, nausea, vomiting, confusion, decreased cognitive function, delayed reaction time or more severe consequences like kidney failure, shock, coma and even death.

With all of this being said, dehydration is 100% preventable … so grab your water bottles and read on!

The Basics:

By definition, hydration is the process of providing an adequate amount of liquid to bodily tissues. 

Optimal hydration requires a balance of both fluids and electrolytes, which are essential minerals in the body.

Electrolytes lost in sweat include sodium, potassium, chloride and magnesium and are necessary for our body to function properly. While most healthy individuals can stay hydrated just by consuming water, athletes or physically active individuals may need to supplement with electrolytes due to a high loss of sweat during intense bouts of physical activity.

Why is Hydration Important?

  • Transports nutrients, oxygen and waste products to all cells in the body
  • Lubricates the joints
  • Moistens tissues in the eyes, nose and mouth
  • Regulates body temperature
  • Gets rid of wastes
  • Water makes up about 75% of your muscles
  • Helps your brain to function properly

How Much Fluid Should I Be Consuming?

You have probably heard of the 8 x 8 rule. Consume eight 8-ounce glasses of water each day. But should you really be drinking this amount of water?

Believe it or not, this recommendation actually stems all the way back to 1945, when the U.S. Food and Nutrition Board of the National Research Council recommended those following a standard 2000 kcalorie/day diet consume 2 L (64 ounces) of total water each day.

Since then, new research has shown this theory to be lacking in evidence. So what did they find? There is no one size fits all when it comes to how much water we should be drinking each day, and there are a variety of factors that will affect daily needs including age, gender, physical activity, outside temperature, environment, illness and disease, and pregnancy or breastfeeding women.

According to the U.S. National Academies of Sciences, the recommended intake of fluid is 

11.5 cups a day for Women

15.5 cups a day for Men

Since we typically meet 20% of our water needs through daily food intake, this translates to about 9 cups of fluid for women, and 13 cups of fluid for men.

What Drinks Help Promote Hydration?

Plain water is best! 

Other good options include zero and low-calorie beverages including tea, broth, sports drinks (especially on exercise days), seltzers, sparkling water, and coffee

Although beverages like soda, juice, specialty coffee and teas, and energy drinks can help increase fluid intake, many are high in calories and added sugars so consume in moderation.

Possible Signs of Dehydration:

Once an individual experiences a water loss of 2% or more of overall body weight, dehydration can occur.

Possible signs and symptoms include:

  • Headache
  • Fatigue
  • Dizziness / feeling light-headed
  • Feeling thirsty 
  • Dark, low volume of urine

Individuals highest at risk include the elderly due to a reduced sensation of thirst, babies and infants, children, alcoholics, diabetics and those working long hours in hot temperatures.

How to Assess Hydration: 

Use WUT: if 2 or more markers are present there is possible dehydration

Weight: Ensure maintaining table body weight from day-to-day within 1%

Urine: Darkened urine first of the morning or reduced daily frequency

Thirst: Dry mouth or craving of fluids

Staying Hydrated when Exercising:

Consume 7-10 oz of fluid every 10-20 minutes during exercise

For every lb of body weight lost during exercise, consume about 16 oz (2 cups) of fluid

Consuming electrolytes or a sport drinks with sodium can aid in hydration by retaining water in the body

Tips for Staying Hydrated:

  • Make it a goal to consume at least half of your body weight in ounces of fluid each day
  • Carry a water bottle with you
  • Purchase a reusable water bottle to keep water cold 
  • Consume foods that aid in hydration such as soups, broths, fruit, vegetables, smoothies, protein shakes, and low sugar sport drinks 
  • Try adding flavor to your water by using fresh fruit and herbs
  • Track your water intake
  • Consume a glass of water first thing in the morning

Is There Such a Thing as Drinking Too Much Water?

While overhydration is not as common, it does exist. 

The kidneys in the body do a great job at excreting extra water through water or sweat. However, if too much water is consumed in a short amount of time, the kidneys may be unable to excrete all of the excess fluid. This causes low levels of sodium in the blood, known as hyponatremia.

Individuals highest at risk include those who are ill and/or who have kidneys that are not functioning properly.

Endurance athletes including marathon runners and triathletes may also be at risk since they tend to consume large amounts of water.

The Bottom Line

It is difficult to know the exact amount of water we need on a daily basis. Many factors will affect this, so being aware of these things and being able to recognize signs and symptoms of dehydration can help make sure we are consuming enough water.

  • Aim for pale or clear urine
  • If you are thirsty, drink!
  • Consume more water on hot and humid days
  • Make sure to drink fluids before, during, and after exercise
  • Consume fresh fruits and vegetables (turns out your dietitians want to make sure you consume enough of these in your diet for more benefits than you think!)

So follow these tips and drink up! (Water … that is!) 


Gunnars, K. (2020, November 5). How much water should you drink per day? Healthline. https://www.healthline.com/nutrition/how-much-water-should-you-drink-per-day

Kenney, W. L. (n.d.). The Impact of hydration on athletic performance. American Council on Exercise. https://acewebcontent.azureedge.net/SAP-Reports/Hydration_SAP_Reports.pdf

Sissons, C. (2020, May 27). What is the average percentage of water in the human body? Medical News Today. https://www.medicalnewstoday.com/articles/what-percentage-of-the-human-body-is-water

Stooki, J.D. & Kavouras, S. A. (2020). Water researchers do not have a strategic plan for gathering evidence to inform water intake recommendations to prevent chronic disease, Nutrients, 12(11). doi:10.3390/nu12113359

RxRD Nutrition

Matt provides nutrition education and lifestyle changes to help people become their healthiest self inside and out.

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