Hey there, I am pretty new to this too...Day5 VLCD....but I was listening to the Pounds and Inches book / Guide and he did mention that muscle aches and fatigue are common, especially at first when the fat is being released from the cells and the body is being detoxed. I have also been very fatigued, have some muscle aches, etc. Hopefully it will pass soon, huh? : )
Oh, I saw on another board where it was recommended to eat a little extra protein when you feel lightheaded or just too weak.