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By Chris Irvin, The Ketologist

When it comes to supplements on a ketogenic diet, there are few that come to mind before MCT oil.  However, MCT oil is hardly a supplement. In fact, it’s the most ketogenic naturally occuring fat that you can get in your diet.  Let me explain. 

MCTs are a classification of unique fats that are found primarily in coconut oil, palm oil, and dairy.  MCT stands for medium-chain triglyceride. Most of the fats we eat are considered long-chain triglycerides or LCTs.  This means that from a molecular standpoint, these fats contain a long chain of carbons. An MCT is a classification of fats that have a much shorter carbon chain length.

You may be wondering, “why does that matter?”  The answer comes in the differences in metabolism due to the length of a fat.  Fats are metabolized by having carbon atoms removed a couple at a time. This means that the shorter carbon chain length of MCTs allows them to be metabolized much more quickly compared to LCTs.  This not only makes them a rapid energy source but it also allows them to be used for the natural production of ketones!

That’s right, MCTs can naturally increase your ketone levels, which is why they are considered the most ketogenic fat.  However, MCTs have so much more to offer than just increasing ketone levels. In fact, there is a large body of research suggesting that MCTs can provide numerous benefits including stimulating fat burning (1), promoting fullness (2), and improving cognitive function (3). 

If you’re sold on the benefits of MCTs, your next question might be, “how do I get MCTs in my diet?”  The answer is that it depends on your goal.

There are technically 4 different fats that classify as MCTs.  They are:

  • Caproic acid (C6)
  • Caprylic acid (C8)
  • Capric acid (C10)
  • Lauric acid (C12)

The C and number next to each MCT represents the carbon chain length of the fat.  Remember, the shorter the carbon chain length, the more rapidly it can be metabolized.  

When you consume a whole food source of MCTs such as coconut oil or dairy, you are getting a blend of all of the above MCTs but primarily lauric acid.  While lauric acid has its own unique benefits, being the “longest” of the MCTs means it is not as rapidly converted to ketones.  

Thus if your primary goal for taking MCTs is to increase ketone levels then you should consider using an MCT oil which is a blend of C8 and C10 extracted from coconut oil leaving you with a much more ketogenic fat source. 

I have to say, I am a big fan of MCTs.  My morning routine always involves a couple hours of uninterrupted and focused deep work.  During this time I am doing a lot of research and writing so I always strive to be incredibly focused.  One strategy I use to assist me during deep work is MCTs.  

Remember, MCTs are rapidly converted to ketones.  Interestingly, research has shown that our brain takes in ketones in proportion to their availability in the blood (4).  That means stimulating ketone production equals more energy to the brain. A great way to get your brain humming along.

To help demonstrate what a beginner could expect when taking MCTs, check out this experiment I did! 

MCT Oil Self-Experiment

In this experiment, I set out to test what a beginner would experience when taking MCTs for the first time with their breakfast.

Since I am no beginner to keto, I carried out this experiment with the help of my friend Dave who is not following keto or in ketosis.

On two different test days, he ate the same breakfast consisting of 3 eggs and 2 pieces of bacon.  On day 1, he just ate breakfast. On day two, he ate breakfast with MCTs.

Before consuming breakfast, Dave measured his ketone levels using the Biosense breath ketone meter. Dave then tested his levels several times for a couple hours after consuming the meal.  

On the MCT testing day, Dave consumed 8g of MCT oil.  It should be noted that this is much lower than what is shown in the research to lead to significant ketone production; however, because it is recommended that beginners consume a lower amount of MCTs when first using them, we went with this dose.  

Breakfast/ No MCTs

breakfast no MCTs

Breakfast + MCT Oil

breakfast with MCTs

As you can see from the graphs, there was a greater increase in ketone levels when MCTs were consumed with breakfast.  However, the change was pretty minor with only a 2 point increase, equivalent to a 0.2mmol increase in the blood.

Based on these results, it seems that if your goal is to increase ketone production, you will want to taper up your dose of MCTs as tolerated.  It’s important to remember that the benefits from MCTs do not just come from ketone production and you can still see health benefits at these smaller, beginner doses. 


MCTs are a unique fat source that has been shown to provide numerous health benefits including increasing ketone levels.  In this experiment the recommended dose for a beginner using MCTs only led to a minor increase in ketone levels. Thus it is suggested that if ketone production is your primary goal, MCT dose should be increased as tolerated.

As a note of caution, be sure to taper your dose of MCTs up slowly.  The unique way MCTs are digested and metabolized can lead to GI distress in those who have never had them.  Start low and increase the dose slowly. Your stomach will thank you! 


  1. Dulloo, A. G., Fathi, M., Mensi, N., & Girardier, L. (1996). Twenty-four-hour energy expenditure and urinary catecholamines of humans consuming low-to-moderate amounts of medium-chain triglycerides: a dose-response study in a human respiratory chamber. European journal of clinical nutrition, 50(3), 152-158.
  2. Stubbs, R. J., & Harbron, C. G. (1996). Covert manipulation of the ratio of medium-to long-chain triglycerides in isoenergetically dense diets: effect on food intake in ad libitum feeding men. International journal of obesity and related metabolic disorders: journal of the International Association for the Study of Obesity, 20(5), 435-444.
  3. Reger, M. A., Henderson, S. T., Hale, C., Cholerton, B., Baker, L. D., Watson, G. S., … & Craft, S. (2004). Effects of β-hydroxybutyrate on cognition in memory-impaired adults. Neurobiology of aging, 25(3), 311-314.
  4. Cunnane, S. C., Courchesne‐Loyer, A., St‐Pierre, V., Vandenberghe, C., Pierotti, T., Fortier, M., … & Castellano, C. A. (2016). Can ketones compensate for deteriorating brain glucose uptake during aging? Implications for the risk and treatment of Alzheimer’s disease. Annals of the New York Academy of Sciences, 1367(1), 12-20.

Submitted by Chris Irvin, The Ketologist.  Chris is a nutrition science researcher and writer with an expertise in ketogenic dieting. Chris holds a master’s of science (M.S.) in exercise and nutrition science and spent his time in graduate school studying the ketogenic diet for performance and therapeutic applications. Chris is the education manager at Perfect Keto and strives to make the ketogenic diet easy and keto science accessible to everyone.

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