The reason ketosis is such a big factor on Cambridge is that a mild state of ketosis suppresses the appetite. It also leads to feeling more energetic and positive.
After the first few days or so, which you may find very tough, ketosis sets in. This means the body is burning fat from the fat stores for energy, instead of the sugary and starchy foods we were eating before starting the diet.
With ketosis comes the bliss of not feeling hungry. Not craving food all day long. This doesn't mean that the diet is easy, far from it, but it is very simple to follow and if you stick to the rules you will lose weight fast.
Good luck!