This 2020 study examined whether the brain’s fuel source can influence a measure of brain aging called network stability—the ability of different brain regions to maintain coordinated communication. Using brain-imaging data from more than 900 adults, the researchers found that network stability begins to decline around age 47, with the fastest deterioration around age 60. Type 2 diabetes was associated with accelerated brain aging in younger participants, supporting a connection between impaired metabolism and cognitive decline.

The researchers then tested whether changing fuel availability could alter this measure in healthy young adults. After just one week on a ketogenic diet, brain networks were more stable than on participants’ usual diets; an overnight fast produced a similar effect. In a separate experiment, a calorie-matched ketone drink stabilized brain networks while glucose destabilized them. The researchers argue that ketones may provide the brain with a more energetically favorable fuel and may also bypass impaired glucose metabolism—potentially explaining why metabolic interventions such as carbohydrate restriction and fasting have benefits for brain health.

https://www.researchgate.net/publication/339672033_Diet_modulates_brain_network_stability_a_biomarker_for_brain_aging_in_young_adults