When you’re following a low-carb or ketogenic diet, it’s normal to feel like your memory is a little foggy at first. Some people even report short-term memory loss or the inability to remember things. So what’s going on?
They can’t lay all of this blame on the ketogenic diet, of course. Researchers have discovered that when you follow a keto or very low-carb (VLC) diet, your body actually switches to using a different and more efficient fuel source.
Instead of relying on glucose as its primary fuel source, your body enters a metabolic state known as ketosis, where it begins breaking down fat for fuel. This is why people who follow a VLC or keto diet typically have excess ketones in their bloodstream, which can be measured with urine testers or blood tests.
When you are training your body to use fat as its primary energy source, several things happen inside your brain that make it function differently than if you were on a carbohydrate-based diet.
Energy Sources for the Brain
The brain uses two types of fuel; glucose and ketones. Let’s look at what happens in each case.
When we eat carbs, our body breaks down those carb molecules into glucose which then enters the bloodstream, where it is transported to every cell in the body and used as a primary energy source. The brain uses glucose as well, and when available, it is used preferentially over any other fuel source.
When the body doesn’t have enough glucose to use as an energy source because we are in a state of insulin resistance or blood sugar depletion, it begins producing ketones from fat instead by breaking down fatty acids.
The liver produces and releases some of the ketones the body uses, such as acetone and acetoacetic acid, while beta-hydroxybutyrate (BHB) is produced mostly in the liver but also from fat.
BHB Kicks Glutamate Out of The Brain
The brain uses glutamate as its primary excitatory neurotransmitter, and it is found in high concentrations in the hippocampus, cerebellum, and other areas.
Glutamate use is not limited to neuroglial cells (cells that support or protect neurons). It can also be taken up by astrocytes which are star-shaped glial cells in the brain that have been shown to play a critical role in memory formation. Its uptake by astrocytes is known as “glutamatergic neuron-glial communication.”
This means that when BHB inhibits the release of glutamate, it also kicks glutamate from astrocytes, reducing its availability for use in a process called “reverse transport.”
This improves long-term potentiation and memory formation. However, some studies have shown that high levels of glutamate could cause neurodegenerative changes, so it’s definitely not something you want to increase.
L-Tryptophan Absorption Is Increased by BHB
Because BHB increases l-tryptophan (the precursor of serotonin) absorption in the gut, it is likely to improve serotonin levels and regulate mood.
This may also allow for a greater release of melatonin since serotonin is known to inhibit melatonin secretion. This would make BHB an ideal supplement for improving sleep quality and memory consolidation by taking it before bed.
Glutamate is a Key Driver of Insulin Resistance
It has been shown that high levels of glutamate are responsible for insulin resistance and obesity, which means BHB will help prevent these conditions.
This may be how it prevents or reverses brain fog associated with memory loss while on keto. I suspect this mechanism will also keep your brain sharp by limiting inflammation and preventing neurodegeneration.
Keto And Brain Health
There is no doubt that keto diets are far healthier than the standard high-carb diet.
It has been shown to reverse epilepsy, improve cognitive performance in Alzheimer’s patients and protect against brain damage caused by strokes. Ketone production has also been linked to reduced inflammation and oxidative stress.
BHB keeps blood levels of insulin low, so it will help prevent or reverse insulin resistance which is one of the major causes of metabolic syndrome, diabetes, heart disease, and elevated blood pressure.
It has also been shown that ketone bodies improve mitochondrial function by supporting brain cell generation and growth.
This also occurs because ketones are a more efficient fuel source than glucose. The brain requires 25-30% of the body’s energy, and blood glucose supplies nearly 100% of that demand.
Using BHB as an alternative fuel allows the brain to use up its glucose stores and start burning fat instead. This means less insulin will be required to regulate blood sugar levels.
This process only begins when the body is in a state of ketosis, which means you don’t have to force it with carb restriction.
Keto Brain Fog Protection
It’s likely that BHB also helps prevent “brain fog” associated with ketogenic diets by preventing the accumulation of glutamate.
This may even allow people to be more productive and feel sharper while on a keto diet since elevated glutamate levels (due to insulin resistance) are associated with brain fog and low motivation.
BHB may also improve mental performance by supporting the release of GABA, which is a calming neurotransmitter that inhibits stress hormones and enhances relaxation.
High levels of stress can cause excess amounts of glutamate in your brain, leading to increased anxiety, impaired memory function, and even depression.
This is supported by a study showing that ketone supplementation significantly decreased anxiety in mice.
This may be due to keto helping to increase brain-derived neurotrophic factor (BDNF), which is an important hormone for memory function, learning, and stress resistance.
The ketone body beta-hydroxybutyrate (BHB) is important for various brain functions because it promotes mitochondrial health and increases levels of key neurotransmitters.
It protects against oxidative stress, inflammation, and glutamate toxicity which may help prevent or reverse memory loss while on keto.
Keto also increases levels of the important memory-enhancing neurotransmitters known as serotonin and GABA.
These are powerful nutrients for improving mental performance and preventing symptoms associated with brain fog like stress, insomnia, and anxiety.
This may be why keto diets have been shown to improve cognitive performance in Alzheimer’s patients and can protect the brain against stroke damage.
BHB is an important brain booster created during “nutritional ketosis,” which is the natural state when your body burns fat for energy.