The biochemical foundation of ketosis represents one of the body's most remarkable adaptive mechanisms. When carbohydrate intake falls below a critical threshold (typically 50g daily), insulin levels decrease significantly, triggering a cascade of metabolic changes. The liver, responding to this hormonal shift, accelerates the breakdown of fatty acids through beta-oxidation, producing acetyl-CoA molecules that exceed the capacity of the citric acid cycle.
This surplus acetyl-CoA is then diverted to ketogenesis, where it's converted into three primary ketone bodies: acetoacetate, beta-hydroxybutyrate (BHB), and acetone. BHB, the most abundant and stable ketone, serves as the primary circulating energy substrate during nutritional ketosis, capable of crossing the blood-brain barrier to fuel neural tissue.
