First of all, there are pro's and con's to being in a state of ketosis and should be applied by only certain fitness specific level people. Always, supplement your body with the essential vitamins and minerals if you ever are in ketosis to replace the nutrients that come from whole carbohydrates.
What is Ketosis? It is when the body is absent of carbohydrates and is in emergency mode. Is that bad? Not as much as you hear people say it is. Yes, carbohydrates is the main source of fuel for the body, but not the only source. The goal of ketosis is to get the body to use fat intake and fat from the body as the primary energy source. The term for that is ketones - which are sources of energy or fat converted into energy. A very good way to get into fat loss mode and retain muscle because majority of nutrients are coming from proteins and healthy fats. As we know that protein is the four walls of the muscle (make up majority of the muscle). It takes about 14 days for the body to get in a true state of ketosis, but in I believe you can get into semi-ketosis if you put a cap on carbohydrate itake instead of just eliminated it.
The first 14 days of getting into ketosis is never very comfortable, but as soon as you are in it that state it is very easy and a smooth ride. There is no HIGHS and LOWS, just a steady state. Fat loss will occur and lean tissue developement will acrue if you are stimulating your body with exercise.
Please remember this is not for everyone and it should only be done if you are prepared to get into such as state. Remember, there is wellness eating and specific type eating. I promote balance eating for the average person, but for someone who is looking to manipulate their body and take it to another level, then this principle could be applied!
Stay Active!!!!