Ketosis is when there are greater levels of ketone bodies in the blood or urine. It comes when ketone bodies are released into the bloodstream due to low glycogen levels in the liver. Ketone bodies are made by a process called ketogenesis. Ketosis can be understood as the use of body fat as a source of energy. Ketosis has 3 main sources of energy, also known as ketone bodies: acetoacetate, acetone, and beta-hydroxybutyrate.