Dept of Family & Community Medicine 3rd stage nutrition Lec - 4 – بسم الله الرحمن الرحيم Dept of Family & Community Medicine 3rd stage nutrition Lec - 4 – By Dr. Muslim N.Saeed December 8th ,2016

Learning objectives 1-Determine percentage of body weight At the end of this lecture student would be able to : 1-Determine percentage of body weight represented by water . 2-Demonstrate functions of water . 3-Discuss water balance . 4-Outline daily recommended allowances of water . 5-Identify the percentage of water in some common foods . To a level accepted to the accreditation standard of the College .

"Water" It is the largest single component of the body weight (55-65%)in adult . It varies among individuals, depending on the proportion of the muscles to adipose tissues. Total body water decrease significantly with the age &is higher in athletes than non athletes.

Percentage of body weight by water according to age and gender

Functions of water 1-Solvent for many solutes (important for the cell function& medium for all reactions). 2-It participates in the metabolic reactions. 3-It acts as a structural material in providing cell forms. 4-Important in physiologic processes of digestion, absorption &excretion of metabolic& indigestible wastes. 5-Important in structure &function of circulatory system. 6-Acts as a transport medium for nutrients &all body substances. 7-Maintains the physical &chemical consistency of intracellular & extracellular fluids& has a direct role to maintain body temperature . Evaporation of 1 Litter of water result in removal of 600Kcal of body heat .

Notes: *Loss of 20% of body water lead to death. *Loss of 10% of body water lead to severe disorders. *In moderate weather adult can live up to 10 days without water while child can live up to 5 days, he can survives for several weeks without food).

Water balance The water content of the fat-free body weight remains constant by homeostatic regulation from interactions among anti-diuretic hormone (ADH), GIT, kidneys & brain. The amount of daily water intake = amount of water lose . In healthy individuals, water intake is controlled by thirst. Water intake water output 1.4L fluid 1.4L urine 0.7L water 0.7L water in feces 0.2L water from cellular 0.45L sweating oxidation of food 0.35L Respiration Total = 2.3 litter 2.3 litter (in normal temperature)

The amount of water lost every 24 hour must be replaced to maintain health & efficiency . Water allowances based on recommended caloric intake is 1ml/Kcal for adults & 1.5ml/Kcal for infants (under ordinary circumstances) or 35ml/kg of usual body weight for adult, 50-60ml/kg for children ,150ml/kg for infants. Thirst is usually an adequate guide for water intake except in infants, in sick & severely tired elderly (decrease thirst sensation) . Any one sick enough to be hospitalized (regardless the diagnosis) is at risk of water &electrolyte imbalance. In lactating mother the need for water is increasing (for milk production) so additional 600-700ml/day water is needed .

Water percentage in some common foods -Bread 35% water -Chicken 67% water -Egg 75% water -Beef 59% water -Milk 87% water -Cheese 42% water -Fish 78% water -Sugar 1% water -Oil 0% water -Soda crackers 4% water -Fruits & vegetables 85-95% water

Thank you all