Ketosis is a state reached when the body is deprived of carbs-the body’s main source of energy- for some time. When this happens, the body is forced to depend on another source of energy; stored fat. The unused fat that has been stored in the body is thus broken down into compounds known as ketones, and these ketones are then used for providing the body with energy. As soon as the body starts depending on fat rather than carbs for energy, ketosis has been reached.
Reducing carb intake and replacing it with a high fat intake can propel your body to start depending on the fat for its energy. But there is another quite simple way: fasting.
Yes, fasting can get you into ketosis. It goes without saying, or you can look at it in this crude way. The body is deprived of all kinds of nutrition (including carbs) for a period of time. It is then forced into generating energy by burning whatever stored fat it can find. But as simple as this may seem, it has to be done correctly to derive the best benefit and not cause health complications to self.