Ilya wrote:
> ... I also don't see any problems using protein for energy, if
>it is plentiful in the diet and the bulk of calories comes from fat.
Yes, I think its ok if
"bulk of calories comes from fat", meaning that enough fat
is available ( starting from about 200grams fat per day ).
Getting only the brains fuel from protein
(500-700 kcal per day and if in ketosis about half of it)
seems to bee easily possible, as inuit, and all the low-carber
and many on the paleofood list experienced.
At least for a limited time.
Getting ones whole energy from protein
(whith less than 80% or so from fat)
brings much more strain and workload for the kidney, liver,
and bone-structure.
I'm not aware of any natural living people who have
managed this for a longer time (inuit have plenty of fat).
>If I remember correctly, when fat is burned incompletely and ketone
>bodies are left over, only 5 calories per gram are used up, 4 are
>'left over' as ketone calories. Thus, about half of the energy
>from fat is going unused FOR THAT PORTION OF IT WHERE KETONE BODIES
>AREN'T USED UP AS WELL. So the question is - exactly how much is
that?
I too haven't got numbers how much percentage of the fat energy
is converted to acetone - and leaving exhaled or urinated.
But acetone is the only ketone body out of three which is unusable.
More ketone bodies could be urinated away in the bodies attemps
to keep the acid balance.
Annother citation supporting this
( at http://medtstgo.ucdavis.edu/endo/lecture/metOrgan.htm ):
!The kidney serves to eliminate noxious material yet preserve
!important metabolites, thus, under normal physiological conditions,
!there is no wastage of glucose, lipid, ketone bodies or amino acids.
!High concentrations of both glucose and ketone bodies are
!filtered into the urine, but under those circumstances,
!their preservation would be more deleterious than their loss.
!... High levels of ketone
!bodies are eliminated in order to maintain acid-base balance.
>I personally don't have an answer, somebody on the low carb exercise
>list posted some calculations (me thinks it was Lyle), but then
>changed them significantly.
If more ketones are excreted to keep the acid balance (by the kidney)
this may be the explanation why the calculations change.
Could you point to the url where that "Lyle" calculations can be
found?
>> I think ketone bodies are a small hope if someone is trying to
>> loose excess kalories.
>If that's the case, then how do you explain people who eat
>FAR above their maintenance levels of calories and still loose
>fat, or don't gain any? I am talking about 5000 calories per day
>in fat and protein. I am also talking about people who used to
>gain weight on 2500 calories per day when eating carbs as well.
Hm, according to the above citation, there are circumstances
when significant amounts (not only acetone) leave the body.
But these don't seem to be normal and healthy.
Why should one want to eat so much as 5000 cal anyway if it's soon
leaving through the kindeys??
Other explanations for the 5000 kcal puzzle were:
5000 kcal fat are about 500g (half liter oil or 2 lbs bacon).
Could that much be assimilated in the gut anyway?
At least it has to be emulsified into small drops by bile
in order to be digested.
If not, it could leave the body as it went into it.
In the same way there's an amino-acid limit (that 55 grams),
and shurely a limit how much gluconeogenesis can build up
from protein
- in the few hours when the protein passes through the gut.
The case with the 2500 carb kcal diet gaining weight:
Any kcal ingested above the actual use is deposited into
fat (except in unnatural circumstances, as above).
I already said how i think that actual *usage* of carb-kcals
is be hindered - lack of enzymes and namely thiamin lack.
So that fat is deposited while at the same time the
energy could be spent useful, because the
body temperature is low, and a fatigueness spares muscle energy.
>> The focus on energy balance should be, IMHO in our
>> intrinsic hunger/appetite regulation.
>Sorry, don't understand what you are trying to say here
Our appetite and hunger feelings regulate how much food we eat.
I think it would be much more easier if the appetite could
say "stop" after the needed 2200 kcal or so are ingested.
Easier as if appetite stops only after 5000 kcal.
It would be easier to feel satisfied after a 2300 kcal meal
as to stop hungry after a 4000 kcal meal.
If we understood what upregulates and downregulates the appetite
this kind of comfort could be achieved.
>> My guess is, that this "set point" is most often determined by the
>> availability of one or few essential micronutrients in food.
>This is a pure speculation on your part. If not - could you
reference
>your sources please.
It's true, this are my own ideas, and i haven't seen them written
anywhere in that form.
I've encountered cites in books and net sites that support
the basics that serve as my basis.
The "set point" reference is in my last posting.
Appetite signals demanding a specific food can be observed by
anybody.
I found reports from animals choosing food Vitamin-b1-specific
or amino-acid specific after a shortage before.
To me, my ideas, may it be speculation, deduction or theory
seem obvious.
I'm interested in all your arguments, ideas and experiences.
regards
Amadeus
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