> Well, and why is it so difficult to hit the ceiling?

Here's one explanation from
http://www.mercola.com/article/Diet/carbohydrates/scientific_evidence_low_grains2.htm

"The level of protein at which this will occur varies,
but it is thought to be possible when protein makes up
30-40% of the calories in an eucaloric diet (the
percent calories from protein can be higher in a
hypocaloric diet). "

"'Rabbit Starvation' (a term coined by V. Stefansson
to describe the phenomenon of excessive dietary
protein) often occurred among explorers who would live
for long periods of time on extremely low fat small
game animals (i.e. rabbits). The condition was marked
by nausea, vomiting, weight loss and fatigue. 'Rabbit
Starvation' was reversible when the percentage of
daily calories from protein began to drop. Although
the 'Rabbit Starvation' phenomenon could effect an
individual consuming a ketogenic diet, it is highly
improbable."

"In general, if one is consuming commercially
available meats (even chicken), the percentage of
calories from fat would be too high to induce this
condition. In the modified low carbohydrate diets, due
to the varied food sources, the risk of protein
toxicity, for all practical purposes, is
non-existent."

> > However, it is also commonly used to describe
> > extreme fat-hunger.
>
> That's the same thing, isn't it?

Not necessarily. Note that 'rabbit starvation' is
"reversible when the percentage of daily calories from
protein began to drop." It does not say, "when the
percentage of calories from fat increases". So, in
theory, the so-called protein 'limit' could be avoided
by increasing carbohydrates. Or could it?

Fat-starvation, on the other hand, would be a
condition where minimal dietary EFA requirements are
not being met. The *only* solution to this condition
would be eating fat.

The distinction seems minor, I know, but it makes me
wonder if 'rabbit starvation' is truly a protein
ceiling issue, or a fat-hunger issue.

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