From: freier@mail.physics.utah.edu (rodney james freier)
Newsgroups: misc.fitness
Subject: Re: Protien consumption
Keywords: protien
Date: 5 Nov 92 19:49:50 GMT
Organization: University of Utah - Physics Department

In article <1992Nov5.173403.16568@cbfsb.cb.att.com>, mmm1@cbnewsf.cb.att.com (mark.m.miller) writes:
|>    I would like some input as to the amount
|> of protien the body can digest and in what
|> kind of time period it is used. I have read
|> that the body can only digest up to 30 gm 
|> of protien at each meal. Which to my understanding
|> this means that anything over this amount will
|> not be utilized by the body.  My friend believes
|> that this is not true. His reasoning is that if
|> you intake say 50 gm of protein at say noon and
|> you do not go to the bathroom until 4:00, the body
|> will utilize all of the protien. But if you go to the
|> bathroom at 12:45 you will loose the unused portion
|> of protien. This does not sound right. Send any replies
|> to the net so that others can read and reply. (or should
|> I say fight it out).
|> 
|>                                 c-ya Mark
|> .
|> 
     I'm no expert, but here's what I know.   I welcome corrections and additional
information. 

  --  I'm pretty sure the Going-To-The-Bathroom-Affects-Protein-Absorption idea
is dead wrong.  Protien is unique among the nutrients in that it contains nitrogen.
This nitrogen is necessary for building tissue.  If the body needs all of the protien
eaten recently, it will use very nearly all of it for tissue maintenance and will not
destroy and excrete much. 
      If the body is not going to use protien for tissue mainenance or construction, 
it has to "deaminate" it.  Once protien is broken down, the nitrogen ends up in uric
acid, which is a toxin, and is then excreted.  (You can tell how much nitrogen your
body is getting rid of by how yellow your urine is.)
      There are two situations that will make the body deaminate protien:
  1)  getting too much protien,  and 2) not getting enough carbohydrates. 
  In the first case, your body will break down the excess protien, store some of the 
resulting stuff as fat or burn it for energy, and excrete the nitrogen.  In the 
second case, WHETHER OR NOT YOU ARE GETTING ENOUGH PROTIEN, the body will have to 
deaminate some to supply the brain with glucose.  It will even destroy muscle 
tissue to get this glucose, if it has to.  

      Now, the GTTBAPA idea is wrong because the body will deaminate protien
whenever it needs to.  The kidneys can remove the uric acid and store it in the
bladder REGARDLESS of when you choose to go to the bathroom.

   --  Next, the body's ability to absorb protien is not as constant as you suggest.
The body will absorb more protien when it needs to.  For example, a person healing
from an injury will absorb more protien because tissues need to be rebuilt.  Also,
protien absorption is the highest about 2-3 hours after strenuous weight-bearing
exercise.  (Weight bearing exercise actually causes small tears in the muscle fibers,
so this is equivalent to the first example.  Muscle growth is the body's way of
healing the injuries and preventing them from being as bad next time.  This is
why you end up so sore after your first workout after a long period without exercise,
and why the following workouts are not as bad.)

     So, if you want to maximize your protien absorption, schedule protien rich
meals after exercise and eat LOTS of complex carbohydrates throughout the day.
Use your urine as an indicator.  If it's clear or light yellow much of the time, 
then you are getting enough complex carbohydrates.  If it's usually dark yellow, you 
are either eating too much protien or not getting enough carbs.

Rod
freier@mail.physics.utah.edu