The first time I did one I jumped right in after having a really awful diet and lifestyle and I understand the headaches completely! I decided to do this one because my poor eating habits were beginning to take over again but this time I slowly began eating a lot more salad and fruits. Even though I haven't been a meat eater in years I was beginning to eat a lot of cheese, certain processed foods for the sake of convenience, etc. and it was taking a toll on my body. I feel really good this time around and I think a lot of it has to do with preparing myself beforehand.