Potassium, magnesium and calcium are the three most important supplements for LCers to take (as when we don't consume all those "enriched" processed foods, we can miss the micronutrients that the manufacturers added).

Another reason for the fatigue could be that you are going through severe withdrawal from carbohydrate addiction. There is a lot scientific evidence that carbohydrates are physiologically addictive. It can be as hard to get off as drugs or alcohol addictions. Give it time and the "physiological hold" that the carbohydrates may have on you should pass.

Good Luck!!

J.