How Can a Keto Diet Support Cognition?

Many factors influence why we sometimes forget where we put our keys or occasionally lose focus, and brain energy metabolism is one of them. Despite only accounting for ~2% of our total body weight, the brain uses nearly one-quarter of our daily energy requirements.1 That is a lot of energy utilization for such a small organ, but it goes to show just how metabolically active our brain is.

While glucose is the brain’s primary fuel source, it has been routinely demonstrated that ketones can largely replace glucose and may offer many additional benefits by doing so. Ketone bodies are a byproduct of fat metabolism and are produced from the fat we eat or from stored body fat via prolonged fasting or by following a very low-carbohydrate, high-fat ketogenic diet. Nutritional ketosis is defined as a plasma elevation of the primary ketone body, beta-hydroxybutyrate (BHB), at levels of 0.5 mmol/L and above.2 Ancestrally, we relied on ketosis during periods of food scarcity, providing the brain with an alternative fuel source in the absence of glucose in order to spare our lean muscle tissue. Today we know that we can mimic this state with a ketogenic diet.3

Many studies have demonstrated positive outcomes using ketogenic therapies in various neurological disorders, most of which report improved cognitive performance.4

While no research has investigated the effect of ketones on cognitive performance in healthy populations, researchers hypothesize that even a healthy brain might benefit from exposure to ketones early, to possibly protect against cognitive decline later on.5 Anecdotally, you may hear people say they experience increased mental clarity while in ketosis, but this still needs to be confirmed by clinical research.

Nutritional ketosis can help increase energy

Fluctuations in blood glucose that occur over the course of a normal day not only contribute to less control over your appetite, but also may lead to reduced mental performance.6   

If you are someone who experiences ups and downs in energy, brain fog, and other symptoms of fatigue throughout the day and reach for carbohydrates to help make you feel better, you may not like to admit it but you could be a slave to food. Relying on a steady fuel source from ketones to support brain function and physical activity is one of the primary advantages of a nutritional ketogenic diet. Think stability: It may lead to fewer unhealthy snacks and naps because ketosis supports better focus and productivity.

No glucose? No problem—ketones to the rescue

As mentioned above, when glucose availability is limited, ketones act as an alternative fuel source.  

To determine whether ketones can fuel the brain even when glucose has seemingly gone from working full-time to part-time, scientists have conducted research that demonstrates whether you are young and healthy or are experiencing age-related cognitive decline, ketones apparently have no issues crossing the blood-brain-barrier and being used as fuel. For this reason, scientists have suggested that ketones may be responsible for improved cognitive outcomes.1 Ketones may promote mental clarity and improve cognition by supplying the brain with energy—when glucose just isn’t sufficient.  

Ketones for healthy mitochondria   

Our cells produce energy by using a fuel source (e.g. glucose or ketones) to power ATP synthesis, our cellular energy currency. Ketone metabolism also produces less reactive oxygen species (ROS) than glucose metabolism. ROS are a natural byproduct of energy metabolism, and when they accumulate, they can cause oxidative stress, which comes natural with aging.7 In this way, ketone metabolism promotes less cellular stress in our brain and may help reduce risk of cognitive decline. Moreover, ketones have been shown to increase mitochondrial biogenesis in the brain and lead to increased energy. Keeping our mitochondria healthy and abundant has been studied to improve cognitive performance, by supporting energy metabolism, and reducing oxidative stress in the brain.8

 For more information on ketogenic diet trends and more, please visit the Metagenics blog.


  1. Cunnane SC et al. Front Mol Neurosci. 2016;9:53.
  2. Volek JS et al. Beyond Obesity Publishing, Miami, FL. 2012:4-5.
  3. Cahill GF. Clin Endo Metab. 1976;5(2):397-415.
  4. Gasior M et al. Behav Pharmacol. 2006;17(5-6):431-439.
  5. Krikorian et al. Neurobiol Aging. 2012;33(2):425.
  6. Yin F et al. Free Radic Biol Med. 2016;100:108–122.
  7. Hajjar I et al. J Neuroinflammation. 2018;15(1):17.
  8. Onyango IG. Gencia Biotechnology. 2018;13:19-25.

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