Dear Arsmith19, Your legs are cold/heavy and you are exhausted because of a potassium deficiency. When you low-carb, you lose a lot of sodium(connected to water retention)and potassium. If you are not taking medications for blood pressure etc. that would hold onto potassium instead of releasing it into your urine, you need to take a potassium supplement. Probably 50mg a day would do but be sure to call your doctor or get advice from a pharmasist. Read the section in "Protein Power" that answers questions about the low carb diet and it's effects on the different systems of the body. You'll find it informative.

Deb