Ketones (beta-hydroxybutyrate, acetoacetate) are produced by the liver during fasting, carbohydrate restriction, or intense exercise. They cross the blood-brain barrier via monocarboxylate transporters and enter brain cells' mitochondria, where they're converted to ATP. The brain can derive up to 70% of its energy from ketones during prolonged fasting.
Ketone metabolism produces more ATP per unit of oxygen consumed than glucose, with fewer reactive oxygen species as byproduct. This 'cleaner burn' reduces oxidative damage to neurons. Ketones also increase GABAergic signalling (calming), boost BDNF production, reduce neuroinflammation, and enhance mitochondrial biogenesis — creating more cellular power plants in your neurons.
Ketogenic diets have been used since the 1920s to treat drug-resistant epilepsy — they work in roughly 50% of patients who haven't responded to medication. The anti-seizure effect comes from ketones' ability to stabilise neuronal membranes and reduce excitatory neurotransmission.
For Alzheimer's disease, the 'type 3 diabetes' hypothesis suggests that impaired brain glucose utilisation is a key driver of cognitive decline. Ketones bypass this problem — Alzheimer's brains can still metabolise ketones efficiently even when glucose metabolism is severely impaired. Clinical trials of ketone therapies (both dietary and supplemental) show cognitive improvements in mild cognitive impairment and early Alzheimer's patients.
You don't need a strict ketogenic diet to benefit. MCT (medium-chain triglyceride) oil is converted directly to ketones by the liver, regardless of carbohydrate intake. Starting with 5ml and building to 15-30ml daily provides a meaningful ketone boost. C8 MCT oil (caprylic acid) is the most ketogenic fraction.
Intermittent fasting naturally produces ketones during the fasting window — by 16-18 hours of fasting, ketone levels are meaningfully elevated. Morning exercise in a fasted state amplifies ketone production. Exogenous ketone supplements (ketone esters or salts) provide an immediate brain fuel source and are being tested for cognitive enhancement. The combination of occasional fasting, MCT oil, and exercise provides ketone benefits within a normal, flexible diet.
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