Ketosis

State in which the body uses fat for energy, producing a substance called ketones, small carbon fragments created by the breakdown of fat stores. Most low carb diets work on the theory that by depriving your body of energy-giving carbohydrates, you force it to rely on fat stores for fuel instead. Urine analysis is the normal method of determining if someone is in ketosis.

Ketosis is often confused with a specific condition called ketoacidosis.