I haven't tried a ketogenic diet yet, though I have considered it.  Someone
told me that ketosis requires the restriction, not only of carbohydrates,
but also of protein; the ketogenic diet is very much fat-based.  I recently
read somewhere (perhaps the raw-food archives) that few ketones were found
in the blood (or was it urine?) of Inuit eating a traditional diet.  This
makes sense to me, since it is difficult to imagine why the incomplete
burning of fat would be desirable.  Therefore, a ketogenic diet may not be
comparable to a low-carb hunter-gatherer diet.  I haven't researched the
subject much, so I hope that someone will correct me if any of my
information is wrong.  Even though the ketogenic diet may be somewhat
unnatural, it has considerable therapeutic value; for example, countless
epileptics have been saved by this diet.

It's not as though a paleo ketogenic diet and the good ol' Standard American
Diet (SAD) are the only two choices.  If there is a common cause which
unites the "alternative" diets (McDougall, the Zone, paleo, etc.), it is a
mutual disdain of SAD.

Cheers,
-- Aaron Wieland