Beta-hydroxybutyric acid, also known as BHB, is a ketone body produced by the liver during fasting or in a state of ketosis. It is a key energy source for the brain and muscles and has been used as a supplement in a ketogenic diet. BHB has several synonyms, including 3-hydroxybutyrate, 3-hydroxybutanoic acid, and 3HB. Other related terms include ketone bodies, ketosis, and the ketogenic diet. BHB has also been linked to health benefits such as weight loss, improved athletic performance, and potential therapeutic applications in neurological diseases like Alzheimer's and Parkinson's.