Metabolism
Ketosis
/ kee-TOH-sis /
Ketosis is a metabolic state in which the body, running low on glucose, shifts to breaking down fat for fuel and produces molecules called ketones as an alternative energy source. These ketones, chiefly beta-hydroxybutyrate, can supply energy to tissues including the brain when carbohydrate is scarce. Nutritional ketosis is generally defined as blood ketone levels at or above roughly 0.5 millimoles per liter.
Ketosis is one of the key beneficial metabolic states fasting can lead to. As stored carbohydrate is depleted, the body increases fat breakdown and ketone production rises, which is the same fuel switch that fasting and a very low carbohydrate diet both arrive at by different routes. The depth of ketosis depends on how long you have gone without carbohydrate and on individual factors, so it varies considerably from person to person.
