What are Exogenous Ketones, Are They Safe, and When to Use Them

Can you achieve ketosis with supplements?  Without following a ketogenic diet? We don’t think so but there may be situations where exogenous ketones can play a role in your ketogenic lifestyle.

When the body is in a state of ketosis, it uses fat instead of glucose as an alternative fuel for energy which breaks down into ketone bodies, that can then be used by the body for energy. Getting into a nutritional ketogenic state with dietary modifications alone requires a significant reduction in carbohydrates which can be challenging for some people. So, can you drink a supplement to get into this ideal state of ketosis for fat burning? 

We’ll explain the different types of exogenous ketone supplements, the conditions in which they may be beneficial, and the research being done in this field.

What are Exogenous Ketones? 

There are two ways the body can use ketones for fuel. One is endogenous, “endo”, which means that it is made within the body. This is when ketones are produced by the liver and excreted in the blood or the urine. These are the natural forms of ketones which the body can make on its own by eating a ketogenic diet.

Alternatively, one can ingest exogenous ketones, “exo”, which means that these ketones are created outside of the body. These ketones are ingested in a pill, powder, or liquid form. 

Exogenous ketones drinks are growing in popularity as a method to increase blood ketone concentrations in the body more quickly than dietary changes. The purpose is to raise your blood ketone level and speed up the process of ketosis because increases in ketone levels through diet alone generally take longer to achieve.  

Types of Exogenous Ketone

Ketone Salts vs Ketone Esters 

The most widely available exogenous ketones supplements come in the form of powdered ketone salts which are more economically priced than esters. 

Less common are ketone esters, which work more quickly (in 10 to 15 minutes, as opposed to an hour for the salts), and tend to result in larger spikes in ketones but they also have a very unpleasant, maybe even unpalatable taste.  

Both can be expensive if taken regularly.

It’s important to review the ingredients in these ketone supplements to determine which type of beta-hydroxybutyrate (BHB) is being used in the product. The most beneficial ketone supplement is made of D (dextro) (BHB) which is the main source of fuel the body runs on vs the L (levo)-BHB or D+L-BHB form.

It’s also important to know the amount of BHB in each serving which is not always disclosed.

Some of the more popular brands include:

(Note: Keto-Mojo has not tested these products and is not making any form of recommendation.)

Medium Chain Triglycerides:

Medium chain triglycerides (MCT) are composed of a mixture of 8 and 10 carbon fatty acids and are efficiently digested to free fatty acids, directly absorbed, and rapidly metabolized by the liver. Although MCT oil is not technically an exogenous ketone supplement, these fats can promote endogenous ketone production. This oil is tasteless and odorless, however can cause gastrointestinal distress at high doses. Learn more about MCT oil here or purchase here

Are Exogenous Ketones Safe? 

Exogenous ketones are not regulated by the FDA, so the ingredients and effectiveness could differ between brands, and claims may not be substantiated. Not all ingredients may be listed on their packaging and some ketone salts have been known to include caffeine. Ketone salt and ketone ester brands can vary significantly in their ingredient list so be mindful about additives when choosing a supplement.

Ketone supplements appear to be safe both for occasional and long-term use and quickly induce ketosis or elevate ketone levels once ingested. Although there is increasing interest in studying its effectiveness in conjunction with the ketogenic diet, there is still little scientific evidence published.

Also, the degree and duration of ketosis is individualized, and you should consider what your goal is for taking them (more on that below).

BHB salts are most often bound with a mineral like sodium, potassium, magnesium, or calcium. This can be beneficial to replenish lost electrolytes from symptoms of the keto flu, however large doses of these minerals could be detrimental for people sensitive to high levels of these minerals or people with high-blood pressure or heart disease.

These supplements may also cause stomach distress. If you intend to take them, we suggest starting with a smaller serving and monitoring your response before working up to a full serving.

It is recommended that individuals discuss with their healthcare provider if exogenous ketones are appropriate to use for them.

The Benefits of Exogenous Ketones

Since the objective behind taking exogenous ketones is to put you in a deeper state of ketosis, it’s no surprise that companies make the same benefit claims as the ketogenic diet itself, including:

  • Increase mental clarity and focus
  • Increase energy and physical performance
  • Burn more fat
  • Decrease hunger
  • Weight loss
  • Decrease inflammation

Exogenous Ketones for Weight Loss

Ketone supplements are not a substitute for the ketogenic diet. When taking exogenous ketones, the body shuts down production of its own endogenous ketones, which can dampen lipolysis which means the body is not breaking down its own fat for energy. That means your body is using the exogenous ketones for energy first, and this can be counterproductive if weight loss is your goal.

On the other hand, elevated ketone levels can curb hunger which may result in eating fewer calories which can result in weight loss.

Exogenous Ketones for Physical or Athletic Performance

There are several new studies on improved athletic performance and supplementing with exogenous ketones. Many of these studies look at their short-term use, in which the data is still unclear but promising. 

In a randomized control trial that was conducted in 2016 which had five separate studies, researchers worked with 39 high performance athletes to review effects of supplementing exogenous ketones as the body’s primary fuel source to potentially create a positive physiological state for trained athletes. The results showed how this metabolic state of being in ketosis, using exogenous ketone ester supplementation, can improve physical endurance by using fat instead of carbohydrates for oxidative respiration. These findings are encouraging for high performance athletes. 

Some studies have shown that exogenous ketones may significantly enhance endurance exercise performance and can blunt symptoms of athletic overreaching such as tiredness, loss of performance, and slow recovery. There are several trials underway, as more research is needed to make definitive statements on the use of exogenous ketones and improved athletic performance for endurance and strength training athletes, as well as untrained athletes. It is also important to identify the use of salts vs esters in athletic performance, as there is some indication that ketone salts could potentially hinder athletic performance.

Exogenous Ketones for Therapeutic Benefits

Clinical trials are ongoing for the use of exogenous ketones in neurological conditions, cancer, psychiatric conditions, Type 2 diabetes/metabolic disease, and many more. 

Alzheimer’s: In 2019, a large review study of multiple papers addressing the same question, was conducted on patients with Alzheimer’s disease using MCT oil to induce ketosis to improve cognition. Although MCT is not considered an exogenous ketone, it provides promise that exogenous ketone supplements in conjunction with the ketogenic diet could potentially have the same, or better effects. 

Parkinsons: Another clinical trial is now underway looking at the benefits of exogenous ketone esters in Parkinson’s disease patients. Several other studies are researching the benefits of exogenous ketones for neurodegenerative disorders in humans and animals. 

Epilepsy: It is well known that the ketogenic diet can be beneficial for seizure control in children with epilepsy by achieving high levels of ketosis endogenously. Preclinical data suggests that exogenous ketones could play a benefit to achieve these high levels of ketosis to supplement the diet.

Cancer: There are also new published articles in humans regarding the benefits of exogenous ketones for preserving muscle mass loss in patients with cancer.  Many studies reviewing cancer patients focus on the importance of measuring the glucose-ketone index (GKI).  It’s been found that maintaining a GKI <1 can reduce the progression of brain cancer. But getting to a GKI <1 requires very high ketone levels and low glucose levels. Many individuals struggle with getting to this level with diet alone, therefore exogenous ketones may be beneficial in this population to achieve this goal to supplement the ketogenic diet. Ongoing research in mice and humans is being studied to determine if the use of exogenous ketones with cancer patients may be a beneficial adjunct to traditional treatments.

Psychiatric: A review article in 2019 discussed the possibility that exogenous ketone supplementation-induced ketosis may be an effective therapeutic tool for psychiatric diseases, as adding ketone supplements to the patient’s therapeutic regimen may reduce symptoms such as neuroinflammation, anti-anxiety, and anti-depressive effects. There is emerging evidence in this field of study, which is encouraging for mental health disorders such as schizophrenia, bipolar disorder, anxiety disorders, major depressive disorder, among others. 

Diabetes: There are also new findings that raise the possibility that exogenous ketones may help those with impaired blood sugar control, such as individuals with insulin resistance and type-2 diabetes. 

Although all of this new research is exciting, more studies are needed to provide direct, specific recommendations for each condition, but the research is promising. 

Conclusion

There’s just not enough peer-reviewed research to make any strong conclusions in favor of ketone supplements but it’s an encouraging field of study. Although these supplements should not be used as a substitute for following a ketogenic diet, they may be useful as a complement to carbohydrate restriction.

Test, Don’t Guess

In keeping with our approach to all things ketogenic, we recommend you test your ketones after taking any exogenous ketone supplements to see if they are effective for you.  In the beginning, we suggest testing at 30 minutes, 1-hour, and 2-hour increments after ingesting the supplement.