Low carb is a natural diuretic.  Do you take diuretics or blood pressure
medicene?  You may be losing too much potassium.

magnesium
potassium

I used to have that problem when low-carbing, not just in the legs but
in the chest and stomach too. I've had some *nasty* cramps.

Potassium is critical to your body, you can die if you aren't striking
a reasonable balance. Don't just try to supplement. Go to a doctor and
look into the problem. Take a blood test and see. If you need
potassium suppliemnts, you need it in a prescription size dose, not
what you would find on the store shelf.

Forget the low-salt, do you know how much of that stuff you'd have to
eat to get a full days dosage? Even then, no guarantees that your body
would either absorb or hold onto long enough (if potassium even is the
problem.)

That being said, I had blood work done my potassium levels where fine.
I took quinine pills for a while and that helped. After a while the
problem cleared up on its own. Some people say that Vitamin E helps --
I never tried that.

Since you're concerned about missing something nutrition-wise from
your diet, and suspect that is why you are having cramps, I'd be
interested in seeing what you typically eat over the period of a
couple days. Could you post that, please?

Mike

As you've seen from other responses, there are several things that you
can try.  Some people get better results from one thing, others from
something else.

For ME the critical thing seems to be magnesium.  Try 500 mg/day of
magnesium oxide (a cheap form) and see if that helps.  If that's also
the critical thing for YOU, it should stop the cramps within a day, or
maybe two days if you're very depleted.

You mentioned taking Potassium - but you don't mention the dose you're
taking.  In the USA, the non-prescription supplements are limited to
99 mg of elemental potassium.  If it has a large number like "650 mg
potassium carbonate" that gets you 99 mg potassium and 551 mg
carbonate".  The recommended daily allowance of potassium is roughly
3000-3500 mg, so just taking a couple of 99 mg pills won't do you very
much good.  Using Lite Salt (half KCl, half NaCl) or even better Salt
Substitute (entirely KCl) in your cooking/on your dinner table is a
fast and cheap way to significantly boost your potassium.  Some people
don't like the taste (most complaints are of a "metallic" taste) while
others have no problems with it.  I find it has a slighly different
"warmth" or "mouth feel" but the taste is just fine for me.  You can
also ask your doctor about precription-strength potassium supplements
(Slo-K 800, for example, gives you 800 mg per pill in a time-release
formula and you might take up to 3/day.)  You need to watch out for
drug interactions, though.  If you are taking "potassium sparing"
blood pressure medications this is especially important.  Note also
that replacing the sodium found in normal table salt with the
potassium in the salt substitutes can also lower blood pressure in
some people all by itself.  Not everyone is sodium sensitive, but a
significant number of people are. This is just another point where
each person needs to find out how THEIR body responds.

As others have mentioned, extra calcium helps some people and quinine
helps some people.  Calcium can reduce the body's ability to absorb
some medications and nutrients so as a default (i.e. until you've
researched it) you should take other medicines or supplements a couple
of hours apart from when you take calcium. A doctor or pharmacist can
help tell you if anything you take would be affected by the calcium.

hey Don forget all that bull about pottassium and salt and just get
this.
Here is  a simple  cure for cramp in the leg calf.
When you feel it coming on, (I normally get a second or two warning
before it
hits home) push your legs straight down if lying in bed and cock your
toes
up towards your face as hard as you can. Hold this rigid position for
several seconds and then relax.
You must think quickly to react as I have stated but it always works
and the
cramp pain is avoided.
Often it is the action of stretching your legs in the bed and pushing
the
toes out and down that triggers the cramp. Once you master the
technique you
will never have another painful  leg cramp.