water. how much water are you drinking? If you are actually drinking your 8 glasses and still feeling wiped out I'd suggest a touch of apple juice in your water. Studies show the sugar helps your body actually use the water and hydrate. If you are hydrated, look next at how much sleep you get, and third at how much you are eating. A friend suggested caloriecountabout.com to me and it turned out I was eating 1/2 the calories I should be (but twice as much fats) once I started eating a full days worth of calories (calories is how we measure energy remember) I felt so much better and actually LOST 5 pounds.