Human Nutrition 3(3+0)
Lesson 45 : Water Functions and Water Balance


Water is considered as the most important nutrient for the body. It forms the greatest component of the human body, making up 50% to 60% of body weight. Lean muscle tissue contains about 73% water. Fat tissue is about 20% water. Thus as fat content increases in the body, total body water content declines towards 50%. Water – the most versatile medium for all kinds of chemical reactions constitutes the major portion of our bodies. Without water, the life processes would cease in a matter of days.

The water content of soft tissues ranges from 70 to 80 per cent while that of bone about 20 per cent.

Body water is distributed as follows:

  1. inside the cells of tissue – intracellular water (50 per cent) and
  2. outside the tissue cells – extracellular water (20 per cent).

The extra cellular water is further sub divided into

  1. water in blood plasma (about 4 per cent);
  2. interstitial waterwater in tissue spaces (9 per cent) and
  3. Lymph in the lymphatic vessels (7 per cent).
Last modified: Wednesday, 15 February 2012, 6:51 AM