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Q: human physiology ( Answered,   0 Comments )
Question  
Subject: human physiology
Category: Health > Fitness and Nutrition
Asked by: barbara53-ga
List Price: $5.00
Posted: 09 Oct 2003 07:37 PDT
Expires: 08 Nov 2003 06:37 PST
Question ID: 264558
Why does my body weight go down 2-4 lbs overnight?  Even if I urinate
once, it couldn't account for that much loss.  Could that much be lost
in respiration and transpiration?
Answer  
Subject: Re: human physiology
Answered By: bobbie7-ga on 09 Oct 2003 08:34 PDT
 
Hello barbara53,

Your body weight decreases overnight due to a loss of body fluids or
water.
The body may lose fluids in a variety of ways:

Urine
Lungs - breathing
Skin- perspiration
Feces

The Australian Kidney Foundation 
http://www.kidney.org.au/renal_resources/fact_sheets/dehydration.pdf


“When you wake up you will often be thirsty because your body loses
water while you are sleeping through breathing and perspiration.”
http://www.simple-living-tips.com/weight-loss.html


The Textbook of Medical Physiology illustrates your body’s daily fluid
loss as follows:

Urine:
1400 ml/day or appoximately 3.3 pounds - normal daily urine loss at
normal temperature.

Lungs:
350 ml/day at normal  temperatures or approximately 3/4 pound

“When your body converts food materials to energy, CO2 and water vapor
are released to the blood stream that ultimately may leave through the
lungs.  Water lost through the lungs amounts to approximately.”

Skin:
“The skin loses another 350 ml/day to insensible perspiration (that
which you do not notice as liquid water but evaporates directly into
the air).  The sweat you do notice as liquid is lost at a rate in
proportion to the surrounding temperature and the level of activity. 
Normal temeprature with little activity can produce approximately 100
ml/day this way while under prolonged heavy exercise this number may
go up to 5000 ml/day or 11 pounds.”


Total fluid loss: between 2400 and 6700 ml/day which is about 6 -15
pounds.


“If one third of this occurs at night, the body weight loss could be
in the range of 2 to 3 pounds.”


Textbook of Medical Physiology
W.B. Saunders Co.
Philadelphia, PA
1976     
http://www.madsci.org/posts/archives/jan2001/978977130.An.r.html


Here is a table from the Southern Africa Union Conference.

Fluid Loss 
                            Normal         Hot       Heavy Exercise
Invisible loss   Skin       350            350       350
Invisible loss   Lungs      350            250       650
Visible Loss     Urine      1400           1200      500
Visible Loss     Sweat      100            1400      5000
Visible Loss     Feces      200            200       200
                 Total      2400           3400      6700

Southern Africa Union Conference
http://www.adventist.org.za/Departments/health_files/celebration/Water.doc


Search Criteria: 
Weigh less in the morning
Overnight water loss
Lose *mls per day through lungs
Fluid loss overnight


I hope this helps. If anything is unclear with my answer, please ask
for clarification.


Best Regards,
Bobbie7-ga
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