Total Body Water consists of Intracellular and extracellular water (water inside the cell and outside the cell). Healthy adults body water should be approximately 45-65% of the total body weight. Ensuring adequate fluid intake throughout the day, dependant upon activity level, will ensure that you stay hydrated throughout the day.

A general guide that you are drinking enough fluid will result in urinating clear fluid in the afternoon.

Water is essential to your body’s process and function.

Did you know?

  • The brain and heart are 73% water,
  • Lungs are 83% water,
  • and the bones in the body are 31% water.

Most of us have heard “ the human body is 60% water” since our time in grade school….because it’s true.

Total Body Water declines as we age

Body water will decline as we age due to a variety of natural physiological processes. By the age of 65, muscle mass in humans drops approximately 25-30%. This is due to a combination of a decrease in muscle fiber diameter (drops of 20-30%) and decrease in muscle fiber number (drops of 25%). Muscle atrophy can begin in the 3rd decade of life and over the course life drop by 48% without resistance training.

The maintenance of muscle mass is extremely important in relation to maintaining normal levels of water considering muscle can be composed of 79% water. Loss of muscle can directly affect total body water.

What is the difference between Intracellular Fluid and Extracellular Fluid?

Intracellular Fluid (ICF) in simplistic terms is fluid inside the cell. By definition, intracellular fluid is the place where most of the fluid in the body is contained. This fluid is located within the cell membrane and contains water, electrolytes and proteins. Potassium, magnesium and phosphate are the three most common electrolytes in the ICF. Intracellular fluid accounts for approximately 66% of your total body water.

Extracellular Fluid (ECF) is fluid outside the cell. By definition extracellular fluid is the fluid that travels in the circulatory system in blood plasma, the liquid component of blood as well as within the lymphatic system. Extracellular fluid accounts for approximately 34% of your total body water.

Water accounts for approximately 60% of body weight in men and 55% in women. The normal range for an adult woman can range from 45%-60%, with males being slightly higher (50-65%) due to larger amounts of muscle tissue, bigger organs, and more hemoglobin and in extension blood (predominantly water).

Total Body Water

How do I find my percent water on an Evolt 360 scan?

Total body water/Total weight = percentage of water

Based on where this person’s percentage is, coaches can dive into their client training/recovery/nutrition to see why a client may be less hydrated.

  • Always Look at ratio/percent of ICF to ECF to gauge more about water in the body. The ICF lies within cells and is the principal component of the cytosol. The ICF makes up about 60-66 percent of the total water in the human body, and in an average-size adult male, the ICF accounts for about 25 liters (seven gallons) of fluid. This fluid volume tends to be very stable, because the amount of water in living cells is closely regulated. If the amount of water inside a cell falls to a value that is too low, the cytosol becomes too concentrated with solutes to carry on normal cellular activities; if too much water enters a cell, the cell may burst and this will result in cell death.
  • The ECF accounts for the other one-third of a person’s total body water. Approximately 20 percent of the ECF is found in plasma. The other third of that is found in the interstitial fluid.
  • If you have more muscle tissue expect to hold more water

To learn more about your body and for personalized macronutrient and supplement recommendations  Download the Evolt Active app and search for your nearest Evolt 360 Body Composition Scan location.

For more information about purchasing an Evolt 360 for your business visit or request an information pack below.