Google for "leptin reset" discussions.  Staying too low in carb intake
too long tends to reduce the levels of thyroid T3 and/or leptin.  I tend
to prefer avoiding that by moving my carb intake up to the 50 range but
it's a common tool among body builders to do 6 days of very low carb
then 1 day of very low fat in a repeating pattern.

As to the one meal issue read Carbohydrate Addicts Diet by Drs Heller or
one of the several books that build on it by the same good doctors
Heller.  Their theory is that it takes an hour for the body to start
releasing extra insulin.  My theory is that the leptin reset aspect of
the carb intake spike increases basal metabolism thus increasing the
ketones in the blood indirectly.  On the surface the two explanations
may seem to conflict but I think they address different effects and time
scales.

I has seen a meal with 80 grams of carb kick me out of ketosis so yes it
can.  But it does not change anything already in the bladder if you
measure soon after and it can do a leptin reset so it can increase the
ketones present a day later.  Timing matters.

One problem with calling them "cheat meals" - If your mind set is a
cheat you may want to use the type of carbs most likely to knock you off
the plan by triggering an addictive behavior pattern.  That's either an
intolerance based binge trigger that you haven't documented or foods
with high enough glycemic load to restart the insulin swings.  Doing it
within the one hour time limit from CAD is supposed to handle the
insulin swing but it doesn't always.

One strategy for making a leptin reset a part of your plan anywhere from
weekly to monthly - Try to do it with the high carb foods you find the
least tempting.  Like wheat a lot but consider brown rice boring?  Then
use brown rice as your staple for that low fat reversal meal.  Okay,
that's two strategies as I included mention that it's a low fat reversal.

Every so often I'll have an Indian style vegitarian low fat meal with
all sorts of legumes and rice and veggies and spices and tea that I
order not sweet.  It does not match my least-tempting strategy as I find
the food very delicious but it is so very different from my usual food
that my digestion isn't smooth with it.  It fails to be tempting for a
different reason than by using the carby foods I find boring.

Ask around and you'll find a pattern among certain dieters who want fast
results.  Folks want to stay very low carb for very long because they
are convinced that if low is good lower must be better.  The loss rate
drops off and often enough stalls.  The limited food variety leads to
temptation to cheat.  A cheat triggers a whosh because of its leptin
reset mechanism but folks who don't want moderate plans and moderate
losses aren't interested in the biochemistry so they don't know about
that mechanism.  They just know that a cheat triggered a whosh but it
also triggered guilt.  So they return to very low carbing and once again
they lose for a while then the rate drops or stops.  This eventually
turns into a negative feedback loop of deprivation dieting alternated
with cheats that use worse and worse carby foods not specifically
planned low fat carby foods.  At some point a cheat kicks them off plan
completely and they quit.

There are a *lot* of people out there who say they tried low carbing but
it didn't work and when you ask them about what they did it was take
pattern.  Fad dieting doesn't work and they had treated low carbing with
a fad diet mentality.