The backs of my legs (typically my calves) ache when I do a fast or detox. I am currently on a "Daniel fast" which is basically vegetables, fruit and water for ten days. Since starting it, the backs of my legs ache (mostly in bed at night) and sometimes keeps me awake. Am I detoxing something, or is my body lacking something to cause this ache? It only seems this part of my body does this. In the past when I was fitter and healthier I did water-only fasts, and for three days I got this achy leg symptom at night, but after the 3rd day it went away and I felt good. Any ideas?