After the 12 day induction phase you should feel better. The first week you may feel drained and have no energy, but I felt that way mainly walking upstairs and not so much during workouts. I am a powerlifter so I don't do ridiculous amounts of volume.
You should consider adding a fiber supplement, potassium, and magnesium. All the protein and getting used to the diet can cause constipation and the fiber helps. The potassium and magnesium help prevent cramps. The first week or two of the diet I get cramps.