Hi Jack!

Without more information, I'm taking a guess here, but it could be a couple of things. First...are you drinking a minimum of 64 oz of water a day? If you are it could be low potassium, which is very common when you first start low carbing. For the first two weeks at least, it's recommended that you supplement with potassium at 200-400 mg. a day along with a calcium/magnesium supplement. That's because the induction phase of the plan has a strong diuretic effect. Pair that with the fact that you are drinking a lot of water and it could mean that you are losing electrolytes. Try taking the potassium supplement along with the calcium/magnesium and see if you feel better in a day or two. Let us know how you're doing.