Zareena Hi, yeah the tiredness is part of the VLCD diet I am afraid, you have to remember 600 calories a day is not much and the body has to work that much harder so you will experience tiredeness throughout I think, although it will not happen every day or every week but it will continue. It also affect each other differently, depends on how you are using up the calories. I myself did not experience tiredness until I started exersise.