When you hear about the keto diet, you hear a lot about ketones. But what exactly are they? Ketones (or ketone bodies) are molecules produced by your liver when it breaks down fat — they become your body’s primary fuel source during ketosis.
Your body produces three types of ketone bodies during ketosis: Beta-hydroxybutyrate (BHB), Acetoacetate (AcAc), and Acetone. Each has a different role and measurement method.
BHB is the most abundant and important ketone body, accounting for around 70% of blood ketones in ketosis. It’s the most efficiently used fuel for the brain, muscles and heart. Blood ketone meters measure BHB directly — this is why blood testing is the gold standard for confirming ketosis. Aim for 0.5–3.0 mmol/L BHB for nutritional ketosis.
Acetoacetate is the first ketone produced during fat metabolism. It can be converted to BHB or Acetone. Urine ketone strips measure AcAc — this is why urine testing is less reliable than blood testing, as it measures a different ketone in varying concentrations.
Acetone is a breakdown product of Acetoacetate. It’s responsible for the “keto breath” that some people experience — a slightly fruity or acetone-like smell. Breath ketone analysers measure acetone. While less precise than blood meters, they provide a non-invasive real-time indication of ketosis. Browse our keto main dish recipes to fuel your ketone production, and explore our gluten-free keto recipes for clean-eating options.