Ilya wrote:

>Amadeus Schmidt wrote:
>> Excess calories can't be just discarded by the body,
>> they *have* to be stored or used.

>Nope, they can and are routinely discarded by the body.
>After all that's what ketostix (urine test strips) measure -
>ketones in urine (which are a perfectly good source of energy,
>but in excess, which the body gets rid of in urine). They
>can also be gotten rid of in breath and I believe sweat.

True, exhaled or urinated ketones are one exception of
the above general rule.
Still it appears to me, that the purpose that kestone bodies are
produced for, is *not* to discard some excess kalories.
(to the opposite, animals or humans eating animal bodies are in
trouble to aquire enough calories and have to convert protein for).
Ketone bodies seem to be a by-product of energy acquisition
from fatty acids, and therefore constitute a (small) energy loss
in this pathway.

I've read at the site:
http://medtstgo.ucdavis.edu/endo/lecture/metlipid.htm
>... Ketone bodies...  A third ketone body, acetone, is
>produced by non-enzymatic decarboxylation of acetoacetate.
> Ketone body formation occurs exclusively in liver and,
>although prominent in both starvation and diabetes,
>it is not known to be under direct hormonal control.
>It appears to occur
>predominantly because of the high rate of delivery of fatty acids
>couple with the removal of oxaloacetate for gluconeogenesis.
>All three ketone bodies, acetoacetate, ß-hydroxybutyrate and
>acetone, readily exit the liver into the systemic blood.
>The body is unable to metabolize acetone,
>and it is eliminated in the urine and exhaled by the lungs.

I think ketone bodies are a small hope if someone is trying to
loose excess kalories.
The focus on energy balance should be, IMHO in our
intrinsic hunger/appetite regulation.

As for example described at:
http://medtstgo.ucdavis.edu/endo/lecture/metappet.htm
>....Most humans, once they
>have physiologically matured, maintain quite a stable body weight.
>As with body temperature, there appears to be a set point for weight
>in each individual.If, as illustrated .., an adult purposely fasts,
>body weight will decrease. Upon refeeding, there will initially be a
>greater intake of food as the body returns to the original set point
>of body weight.

My guess is, that this "set point" is most often determined by the
availability of one or few essential micronutrients in food.

regards
Amadeus

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