Someone (Todd, maybe) recently suggested more than a week in ketosis could
lower your metabolic rate and/or was less tolerable etc....  (Can't find
that Digest/too many in my mail box right now!) :-(

Whether a ketogenic diet causes a reduction in metabolism would be a matter
of the calorie level (level of deficit below basal metabolic needs), total
amount of protein consumed (relative to fat), and perhaps individual
differences. There can be many roads to the same place:  ketosis.  It would
be possible to go into deep ketosis, with a signficant caloric reduction,
and then to either slightly increase calories from fat and/or protein or to
cycle calories (with same macronutrients) without resorting to carb
loading/bingeing.  Doing a week at maintenance calories every few weeks or
months (if one wants to lose weight) would prevent metabolic slow down as
far as I know.    See also, Lyle McDonald's book on Ketogenic Dieting.  It
is the most thorough discussion on the topic I have ever seen/read.

In my experience, going very low in carbs for a week or two, then eating
lots of bananas and dates (to carb load) and for a "treat" only led to
massive methane.  (No treat!!!)  Having gone into deep ketosis, recently, I
can say that it feels fantastic (to me), and I don't even want a
banana-binge!  A few grapes here or there is sufficient.  Maybe you'll have
to experiment.  Also, one need not do meat and fat alone--I ate/eat a lot of
green salads....though I didn't want big ones nor as many during my first
week or so in deep ketosis.

Food for thought.
My 200 cents worth,
Rachel