On Sat, 22 Jul 2000 22:17:53 EDT, Gawen Harrison <[log in to unmask]> wrote:

>... humans can only handle 3-5 ounces of meat at one time. I have never
>seen any research that supports
>that statement.  I only get "everyone knows that's true," whenever I ask
>anyone about that statement.
>Does anyone have any info on that subject.
>
I also found only quotes and claims about that maximum.
A possible way of estimation is the protein capacity by the blood.

The whole blood of an adult human (70kg) can hold a maximum of about 55g of
amino acids.
One day will use about 0.4*70 = 28 g of the ideal amino acids for protein
synthesis, from 20 to... high amounts for caloric usage.
This means the 55g amino acids in the blood will have to be
refilled in about one day.

If it's more, then more amino acids will be used for glucose synthesis.
This matches Todd's explanation that after some amount the insulin response
will be higher.
With high caloric usage of amino acids,the turnover rate per day will be
higher, depending on the (possible) rate of emptying by gluconeogenesis.

3-5 ounces ... 5 ounces are 141 g meat, when extra lean this is
23 g of protein.

When the whole blood storage of 55g was empty, then the body might absorb
a maximum of 55g protein (10 ounces meat).
If its half emptied (e.g. after a 12 hour fast) then 28g protein could
be *absorbed*.
As fully depleted amino acid stores aren't probable, assuming a maximum
absorbing capacity of 20-30g seems reasonable.

In the light of the maximum storage capacity of the blood, the 3-5 ouces
limit makes sense.
For a more conservative refilling of the 55g - max. twice a day.
For a high gluconeogenesis rate more often per day.

regards

Amadeus