What are Exogenous Ketones?


Whether you have been around keto for a while or you are new to it, chances are you have stumbled across exogenous ketones at some point.  This supplement has been a topic of hot debate the last couple of years. You may have heard good things about them or you may have heard bad things about them.  

In my opinion, much of the negativity around exogenous ketones stems from a dislike of the companies who are selling them rather than an actual understanding of what this supplement is, what it does, and how to properly use it.

The problem is that many companies have marketed exogenous ketones poorly.  They have promoted using this supplement as a replacement to the ketogenic diet rather than a compliment to it.  I believe that exogenous ketones do have a purpose and when strategically used, can provide benefits.

Before diving into this article, I will start by saying that I do work for Perfect Keto, a company that sells exogenous ketones.  However, I have been a proponent for exogenous ketones since I was in grad school, when I was experimenting with raw BHB. This was long before Perfect Keto and many other exogenous ketone companies were even around.  

Now let’s dig in!

What are Exogenous Ketones?

On a ketogenic diet, the liver produces ketones from the breakdown of stored body fat.  These ketones are also known as endogenous ketones, meaning they are made inside the body.

Exogenous ketones are supplemental ketones that possess a very similar molecular structure to endogenous ketones.  Exogenous means coming from outside the body. When ingested, exogenous ketones are absorbed into the bloodstream causing an increase in blood ketone levels.

While this is still a growing body of research, so far it seems like exogenous ketones could provide numerous benefits and their ability to be metabolized like ketones produced inside the body, gives reason to seriously consider the effectiveness of this supplement.

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What are the Benefits of Ketones?

Every cell in your body needs energy to carry out necessary functions.  For most cells, this energy can come from glucose, fat, and ketones. Certain cells, like brain cells, can only use glucose and ketones for energy. This is why on a ketogenic diet, we see an increase in ketone uptake in the brain. You are no longer providing energy in the form of glucose so the rest of the body transitions to burning fat and producing ketones.  The brain takes those ketones in and uses them for energy.

In fact, when available, ketones are the preferred source of fuel for the brain and produce more energy per unit than glucose meaning that they can provide a greater boost in cognitive function.

To put it simply, exogenous ketones are an energy source.  Supplementing with them can provide your body with a readily available source of fuel.  One that if you are on a ketogenic diet, you are very accustomed to utilizing.

Since exogenous ketones can increase the amount of ketones available for use, reported benefits are:

  • More Energy

  • Improved Mood

  • Improved Mental Focus/ Cognitive Function

  • Better Exercise Performance

  • Reduced Hunger

In addition to these reported benefits, there are many other not as noticeable yet extremely important benefits that research is suggesting could occur from exogenous ketone use.  This research is still in its infancy and needs much more work but is promising. Below is a list of some emerging areas of benefit from exogenous ketone use.

Improving Mitochondrial Function:

It has been noted that using ketones for energy can lead to improved mitochondrial function.  Mitochondria are the parts of the cell responsible for burning fuel for energy. Improving mitochondrial function can reduce risk and improve symptoms of many of today’s most popular chronic diseases.

Activating Brown Adipose Tissue (BAT):  

BAT is metabolically active tissue that is responsible for burning calories.  Animal research has suggested that ketones may be able to activate this tissue, stimulating calorie burning.

Sparing the Breakdown of Muscle Proteins:  

Research has shown that ketones can spare the breakdown of the muscle protein leucine preventing the loss of muscle.  This is one of the reasons why keto is known as a “muscle-sparing” diet

Activating Muscle Protein Synthesis:

There is also some limited animal research suggesting that ketones can stimulate muscle protein synthesis (MPS).  MPS is a regulator of muscle preservation and growth. Much more research needed in this area.

Reducing Inflammation:

Research has shown that ketones may be able to inhibit the NLRP3 inflammasome thus reducing inflammation.  It has also been suggested that ketones may be able to stimulate natural antioxidant production further contributing to the inflammation lowering power of the ketones.

Generally speaking, since ketones possess an ability to reduce inflammation and improve insulin sensitivity, two common contributors to many chronic diseases, I speculate that exogenous ketones could provide therapeutic value for numerous conditions.  Three that stand out to me most are:


Neurodegenerative diseases like Alzheimer’s and Parkinson’s are characterized by an energy crisis in the brain.  This is due to insulin resistance of the brain, or the inefficient ability to take in glucose and use it for energy.  Since ketones produced on a ketogenic diet can help fill treat this energy crisis, I speculate that exogenous ketones could help do the same.


There is some interesting animal research suggesting that exogenous ketones may be able to help treat symptoms and improve the outcome of those suffering from traumatic brain injury.


Keto is finally being taken more seriously for its ability to impact cancer treatment and for good reason.  Early research has indicated that through several proposed mechanisms, ketones may be able to provide anti-cancerous benefits.

In addition to these therapeutic potentials, there is evidence that the signaling capabilities of ketones could give them a unique ability to impact our health at a genetic level, potentially providing numerous therapeutic benefits.

What Exogenous Ketones Are Not

Just as important as what exogenous ketones are is what they are not.  Here is my short list:

A Weight Loss Supplement: Since endogenous ketones are made when we are burning fat, many people tend to look at them as a weight loss supplement.  While there are several indirect ways in which they may be able to contribute to weight loss, they are not a weight loss supplement.

Replacement to a Ketogenic Diet: Many people like to say since these molecules can mimic what occurs in the body on a ketogenic diet, that taking these supplements can be used instead of following the diet.  This is not the case and using exogenous ketones while not on a keto diet will not produce as many benefits.

A Reason to Cheat: While ketones could minimize symptoms of being kicked out of ketosis, they should not be considered a cheat aid.  They will not force you back into ketosis after you eat a pizza but what they may do is reduce the grogginess that may accompany eating that pizza.  Regardless, they do not make cheating healthy and should not be used as a crutch for a consistent lack of self-control.

Going to Stop Your Endogenous Ketone Production: One of the common concerns I hear in the keto is space is that the use of exogenous ketones will stop the body from producing its own ketones.  This is true but this also is not a problem. Our body has a feedback loop that turns off ketone production when there is enough available to meet the current demands of the body.  Taking exogenous ketones will likely activate this loop for a short period of time until those ketones are used and the body needs to start producing ketones again.

Whenever I have tested exogenous ketones on myself, I have noticed that my ketones increase for 2 hours then they return to baseline.  They don’t go to zero. So this isn’t something that I am concerned with or have seen a reason to be concerned with

Different Types of Exogenous Ketones

There are two different exogenous ketone supplements, ketone salts and ketone esters.  There are several differences between each of these with the most notable being the form they come in.  

Ketone salts come in a powder form and are made from binding ketones to various minerals like sodium, calcium, and magnesium.  Ketone esters on the other hand come in a liquid form and are created through an organic pinacol coupling reaction.

Research has yet to determine which of these supplements is more effective and there has been much debate.  My opinion is that each type of ketone supplement has a different use.

Ketone esters can more rapidly increase ketone levels and drive blood glucose down compared to ketone salts.  This could make them more beneficial in situations like concussion treatment, cancer, epilepsy, and other therapeutic instances.  In addition, elite athletes may benefit from this type of supplement but self-experimentation is recommended before implementation.  Keep in mind, many of us are not elite athletes so take that into consideration when thinking about ketone supplementation.

If you are looking for a more modest and sustained increase in ketone levels, ketone salts may be your preferred choice.  This could be good for aiding in keto-adaptation, improving mental focus, increasing energy, and using as a pre-workout. Additionally, if you are going to be using ketone supplements frequently, salts are much cheaper.

Worth pointing out is that an additional benefit to ketone salts is that they are paired with electrolytes. Electrolytes are essential to replenish on a ketogenic diet and using ketone salts is a great way to do so.

When are Exogenous Ketones Best Used?

One specific time when exogenous ketones can be especially beneficial is when you are first starting keto. keto-adaptation is a transition period you experience at the start of keto and during this time the body is still getting accustomed to producing ketones.  Getting a boost from exogenous ketones can help provide energy during this time.

Furthermore, introducing your cells to ketones can upregulate MCT transporters or the transporters necessary for bringing ketones into the cell.  When this occurs, the body becomes more efficient at using the ketones it is producing. I think that increasing blood ketones through exogenous ketone supplementation when first starting keto could enhance keto-adaptation through this mechanism.

Finally, ketone salts are bound to electrolytes that we are deficient in on keto and lead to many of the keto-flu side effects.  Replenishing these electrolytes can help minimize keto-flu symptoms. Another reason to consider using exogenous ketones at the start of keto.  

Besides at the start of keto, there are many different times when exogenous ketones can provide benefit, such as:

  • Anytime you need more energy

  • To provide energy for workouts

  • To reduce appetite

  • To improve brain function

  • To minimize symptoms of being kicked out of ketosis

In addition, exogenous ketones may be great for someone who is looking to transition out of keto and into a low carb lifestyle.  While I do think that exogenous ketones are best used on a keto diet, they can provide benefit to someone who is eating a slightly higher carb diet and not maintaining a deep state of ketosis. However, I do not think they will provide as much benefit to someone who is on a high carb diet.

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Are Exogenous Ketones Safe?

Despite what everyone is saying around the internet, there is no reason to think that exogenous ketones are unsafe and the research we currently have suggests the same. If you have uncontrolled diabetes, that is diabetes that you are not controlling with a ketogenic diet, then the use of exogenous ketones may need to be avoided.    

The only major side effect noted in research is upset stomach but all of these studies are done with people consuming very high doses of ketones.  If you have never taken exogenous ketones, a high dose at the start can cause upset stomach, similar to what we see with MCT oil. For this reason, I recommend starting at ¼ of the recommended dose of whatever product you are taking and increasing your dose as tolerated.  


It is important to point out that if you are considering using exogenous ketones just to increase ketones, I wouldn’t bother.  No research has suggested that having higher ketone levels is better. While I think that there may be some therapeutic cases in which higher ketones may be more beneficial, for the general population I do not think this is the case.

Besides that, I truly believe that exogenous ketones have their place when used in conjunction with a keto diet.  When used strategically, I think they can provide numerous benefits. I look forward to more and more research coming out so we can better understand the potential of these impressive energy molecules!

Ketologist Tip:

My product of choice is Perfect Keto because they dose their product correctly, they don’t use any garbage ingredients and they taste good.  Here are my three favorite times to use this supplement.

  1. Before a workout

  2. Before a focused work session

  3. After 3pm when I need energy but would like to avoid caffeine

If you want to see some of my self-experiments with exogenous ketones.  Refer to my exogenous ketone self-experimentation thread.

Christopher Irvin