Because your feeding your muscles carbs pre and post workout so it keeps the intensity and pumps in the gym and leaves your muscles looking fuller, whereas on CKD I found I would have a rough time in the gym the last couple days before my carb up and look flat. If your going for single digit body fat making gains might be out the question depending on how steep you caloric deficit is. I like to do one day of no carbs and cardio to get into ketosis faster and follow TDK protocol. But I don't cut to get into single digits.