Total Body Water

Our bodies are approximately 60% water by weight.

Men have a higher percent TBW, 60%, due to a greater amount of lean muscle mass.

Women have a larger amount of anhydrous adipose tissue, and their TBW comprises approximately 50% of their weight.

As we age, lean muscle mass decreases, adipose tissue increases, and our percent TBW decreases.

Total body water (TBW) reflects the body’s fluid status, which is crucial for maintaining homeostasis, organ function, and the effectiveness of various treatments.

Total Body Water (TBW) estimated in clinical practice

Why knowledge of Total Body Water is important?

Fluid and Electrolyte Balance

Dosing of Water-Soluble Drugs

Assessment of Nutritional and Hydration Status

Guiding Dialysis in Kidney Failure

Body Composition Analysis

Critical Care and Perioperative Monitoring


 

Fluid Environment of Cells

Digital World Medical School
© 2026