Ketone Supplements Cognitive Performance: What a Drink Does

Ketone supplements were linked to a modest but real gain in cognitive performance in a meta-analysis of randomised trials, but a drink is not the same as being in ketosis. A drink raises blood ketones for a few hours. Ketosis means your liver makes them all day. Much of the benefit showed up in older adults with mild cognitive impairment or Alzheimer's disease, so a fit 40-year-old should measure his own response instead of taking it on faith.

Do ketone supplements improve cognitive performance?

Yes, a little, on average, in the people who were studied. On ketone supplements cognitive performance, the evidence says this: a systematic review and meta-analysis in Frontiers in Nutrition pooled randomised trials of exogenous ketone bodies and found a small but significant improvement. A trade report on the paper counts 29 trials and over 1,100 participants, with ketone esters and MCT oil both included.

Here is the real problem. The supplements were very different from one study to the next. Long-term data barely exists. And a big share of the trials gave MCT oil to older adults whose brains were already struggling. A pooled average across all of that is a signal. It is not a promise about your brain.

How does the brain use ketones?

The brain burns ketones as a second fuel next to glucose, and it uses more of them the higher blood levels climb. The evidence says that in prolonged starvation the brain switches largely to beta-hydroxybutyrate, which spares muscle protein.

In 600 Burgers in 30 Days, Dr. Dom D’Agostino gives his view that the brain can run on glucose and ketones together. That is his reading, not a result from the trials above. Ketones do not replace glucose. They share the load.

That is why the older-adult trials make sense. The evidence says ketones can partly rescue the brain’s energy deficit in ageing and mild cognitive impairment, a review whose limits are small trials and no healthy young adults. A brain short on fuel has more to gain from a second tank than a brain that is already full.

Is drinking ketones the same as being in ketosis?

No.

• Esters: the evidence says ketone ester drinks raised blood beta-hydroxybutyrate to 2.8-3.5 mM within an hour.
• Salts: the same study found salts raised it less, about 1 mM, with a large sodium load.
• MCT oil: a fat your liver turns into ketones quickly, the form used in many of the older-adult trials.
• Your own ketosis: low carbohydrate intake, lower insulin and fat as the main fuel, all day.

One vehicle, two routes. A drink can top up the tank. It does not change the engine. Carbohydrates in your next meal still run the show, and the evidence says both drinks lowered glucose and free fatty acids, which tells you the body is reacting to a dose, not adapting to a diet.

What happened when I tested ketone salts on myself?

They moved my numbers, modestly, and they wrecked my stomach. In my experience, written up in 600 Burgers in 30 Days, I held my breath for 64 seconds at baseline, took 12 g of ketone salts, waited 2.5 hours and held for 80 seconds. My final trial was 93 seconds with blood ketones at 1.1. The salts then gave me around 36 hours of gastric distress.

The film shows the same test. My ketones went up by 0.7 after the 12 grams, and I say on camera that the exogenous ketones “did not raise my levels any more than just not eating all day” (The Keto Project). That is not hyperbole. A day of fasting did the same job for free.

Was the longer hold the ketones? The honest answer is I cannot tell you. It was one man, three holds, one day, and practice alone improves a breath hold. That is exactly why I call it a pilot.

Why might a result in frail older adults not apply to a fit 40-year-old?

Because the benefit looks biggest where the brain is short on energy, and a healthy, trained brain usually is not. A gain measured in people with mild cognitive impairment tells you little about a man who already sleeps, trains and eats well.

The evidence in healthy people is mixed. A pilot in military personnel found two weeks of keto induction did not change cognition, mood or sleep but tended to lower heart rate variability. A second trial found that after a 2-week ketogenic diet, vigilance and memory held up better during 36 h without sleep, a small, exploratory result. Context matters.

Fit people are not immune to diet, either. The film shows Dr. Mike, a fit doctor, eating 20 plain Burger King patties a day for 30 days, no bun, water only. His HRV was cut in half within a week. Dr. Mike wrote of dizzy spells, nausea and setting alarms to remind himself to eat. The film suggests that being fit is no shield. What his brain scans showed is in the film.

When should you take ketones, if at all?

Only as a measured experiment, at the moment you plan to test, with a baseline taken first. If you aren’t testing, you’re guessing.

Here is the test. Take a blood ketone reading and a simple cognitive or breath-hold score fasted. Repeat on a normal day, then after a drink, then after a day without food. Change one thing at a time. Individual results vary, and your gut may vote before your brain does, as mine did.

If you train fasted or on all meat, read what training on an all-meat diet feels like and why fasting glucose runs high in ketosis before you judge your numbers.

Frequently asked questions

Many people feel steady energy and less hunger, but the first week of a ketogenic diet often brings headache, fatigue, nausea and brain fog. Forum reports describe this keto flu peaking early and fading within weeks, according to a qualitative study of online posts (https://pubmed.ncbi.nlm.nih.gov/32232045/). Those are self-reports, so measure rather than assume.

Ketones are fuel made from fat when carbohydrate is scarce, used by the heart, muscle and brain. They also act as signals. Dr. Dom D’Agostino describes anti-inflammatory and epigenetic effects in 600 Burgers in 30 Days, though much of that research comes from cells and animals before humans, so treat it as promising rather than settled.

Many do not. In 600 Burgers in 30 Days, Dr. Dom D’Agostino says that maybe 70 to 80% of what his lab tests does not elevate ketones. A blood meter before and after a serving is the only way to know whether the product you bought does anything at all for you.

They are a rough guide at best. In the film I say a urine strip is not the most accurate method to check for ketosis, because my reading dropped after I drank water. A finger-prick blood meter gives a real number you can compare from one test to the next.

The Bottom Line

A ketone drink is a dose. Ketosis is a state. The meta-analysis shows a modest average gain, mostly in brains that needed help, and it cannot tell you what a drink will do for yours. Measure your baseline, change one thing and write it down. What will you do with it?

If you want to see what happened when a fit doctor ate 600 burgers in 30 days with bloodwork, HRV and brain scans along the way, watch The Keto Project on Prime Video. How it ends is in the film.

Sources

• The effect of exogenous ketone bodies on cognition across health and disease: a systematic review and meta-analysis (Frontiers in Nutrition)
• Meta-analysis supports cognitive performance benefits of ketones (NutraIngredients)
• Stubbs et al. On the Metabolism of Exogenous Ketones in Humans (PubMed)
• Myette-Côté et al. Ketones and brain energy rescue (PubMed)
• Cahill. Fuel metabolism in starvation (PubMed)
• Shaw et al. Ketogenic diet in military personnel pilot (PubMed)
• Henderson et al. Ketogenic diet and cognition during extended wakefulness (PubMed)
• Bostock et al. Consumer reports of keto flu (PubMed)