ketone bodies

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ketone bodies Acetoacetate, β‐hydroxybutyrate and acetone; acetoacetate and acetone are chemically ketones; although β‐hydroxybutyrate is not, it is included in the term ketone bodies because of its metabolic relationship with acetoacetate.

In the fasting state (from about 4 hours after a meal), fatty acids are mobilized from adipose tissue as a metabolic fuel. Most tissues have only a limited capacity for fatty acid oxidation; however, the liver can oxidize more than is required for its own needs. Acetoacetate and β‐hydroxybutyrate are formed from fatty acids in the liver, and are transported in the bloodstream for use as metabolic fuels by other tissues. Acetoacetate is chemically unstable and breaks down to acetone, which is poorly metabolized, and is excreted in the urine and on the breath.