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What are Exogenous Ketones and Should You Take them?

Louise | February 7
What are Exogenous Ketones and Should You Take them

You’ve probably heard them mentioned on various keto diet blogs: exogenous ketones

There are many misconceptions surrounding exogenous ketones – they’ve been getting a reputation as a “magic bullet” or “shortcut” to ketosis, weight loss, and other health benefits…all without needing to follow a keto diet.

But is this really true? While they certainly have a variety of uses and benefits, we’re going to clear up the facts about exogenous ketones for you in this article (plus video).

Q&A Video on Exogenous Ketones

We recently did a rapid-fire questions round with Alex Cunningham from Perfect Keto, and he answered your most common questions on exogenous ketone supplements:

Here are the questions covered:

  1. It seems that it would help with brain power energy but not be helpful with weight loss as we would stop burning our own fat to make ketones… is that true?
  2. Why do exogenous ketones have to be so salty?
  3. Do they really get you into ketosis? And within an hour or so?
  4. Is it better to do ketosis naturally or with a supplement?
  5. What do you personally use ketone supplements for?
  6. What’s the difference between MCT oil and ketone supplements? Does MCT oil boost ketone levels?
  7. Can ketone supplements help you lose weight?

About Alex:

Alex was born and raised in San Francisco and graduated from Villanova University with a B.S. in Chemical Engineering. He’s passionate about nutrition, breaking down health myths, trends in the health food industry, the piano, and Bay Area sports. Alex is the Head of Partnerships for podcast episode you feel like you’d like to try exogenous ketones a try, you can check out our very own Keto Upgrade.

What are Ketones?

Let’s go back to basics a bit…when you go on a Keto diet, you restrict net carbohydrate intake to below 20-25g per day.

And after a few days…

Your blood glucose levels fall as you deplete your glycogen stores and your cells can’t rely on glucose as their main fuel source anymore. There just isn’t enough to meet their needs.

You effectively force your body to start burning stored fat.

And one of the by-products of your liver breaking down the fatty acids is ketone bodies.

While many of your cells can use fatty acids and glycerol directly as fuel, your brain cells cannot. And so in the absence of glucose, your body will send ketones to your brain to fuel it.

These ketones are produced in your liver through the breakdown of fatty acids in a process called ketogenesis.

What are Exogenous Ketones? And how are they different from those produced in your body?

There are actually two different types of ketone bodies….

The ones your body produces naturally are called endogenous ketones.

And the artificially produced ketones you take in the form of a powder/pill/oil supplement are called exogenous ketones.

Endogeneous ketones come in 3 varieties of molecule…

  • Acetone
  • Acetoacetic Acid
  • Beta Hydroxybuyrate (this actually gets converted to one of the previous two molecules before your body uses it)

…while exogeneous ketones are usually in the form of Beta Hydroxybuyrate

  • Why? Because it’s the easiest molecule out of all 3 natural varieties to turn into a nutritional supplement

Now that we’re clear about what the different types of ketones actually are, let’s dive into the different types of ketone supplements…

The 3 Types of Real Ketone Supplements (and a FAKE one)

If you’re looking out for keto supplements to buy, you’ll likely come across these four types.

Type 1 – Ketone Salts

This is the type that most folks who use ketone supplements end up buying.

They’re made of Beta Hydroxy Butyrate combined with a salt (like sodium or potassium) and that’s where the name comes from.

Registered Dietitian Justin Robinson, RD explains, “Ketone salts are commercially available, relatively affordable (~$4/serving) and palatable (taste similar to sports drinks). They have only a mild impact on ketone levels, usually raising blood ketone levels to around 1 mmol, and carry a high salt load (as the ketone body chemically needs to be attached to sodium, potassium or magnesium).”

Type 2 – Ketone Esters

These are currently used mainly in research by scientists – but you won’t be missing out on much by avoiding them.

Although they raise your blood ketone levels considerably more than ketone salts, they have some disadvantages.  Dr. Stephen Phinney, M.D., PhD and Dr. Jeff Volek, PhD RD explain, “The keto-esters are more appropriate for delivering higher doses of BOHB, but with repeated dosing can push the limits of taste and GI tolerance.”

In other words, they also have a very strong and unpleasant taste (making them hard to swallow) and can cause digestive distress.

Type 3 – Ketone Oils

The most common type of ketone oil is MCT oil (aka Medium Triglyceride Oil).

It’s slightly different to the other types of supplement, because MCTs aren’t actually ketones (although your body converts them into ketones).

Once the MCT oil enters your body, it gets transported to your liver, where it is broken down into ketones.

Functional Nutritionist Dr. David Jockers, DNM, DC explains, “MCT oil is a concentrated extract from coconut oil. It is significant because when consumed, it is very quickly converted into ketones with very little metabolic demand from the body. It is almost like consuming table sugar, in fat form, and without the massive crash. Instead you get nice steady energy without any negative side effects.”

Unlike the ketone supplements mentioned above, it doesn’t have such a rapid or strong impact on your blood ketone levels.

NOT REAL – Raspberry Ketones

These are a common sight in the supplement aisles of pharmacies and health stores – and they have nothing to do with ketone bodies or ketosis, and there’s no credible science suggesting it helps with weight-loss.

So which of these 3 Ketone Supplement Types is most effective for weight loss?

One study compared all 3 types of ketone supplements and found ketone esters to initially be the most effective… but by the time 4 weeks had gone by, the ketone salts had caught up in efficacy.

But do you really need to buy ketone supplements at all?

You decide: in the next sections, we’ll go over what health benefits you can expect from ketone supplements and the best ways to use them.

A popular question that gets asked a lot is this…

Can you eat junk and just take exogenous ketones?

You’ll have seen plenty of articles on the health benefits of ketosis.

But you can’t just eat a standard American diet (SAD) filled with carbs all day and hope that taking exogenous ketones will rescue your health!

Raising your ketone levels by carb restriction (nutritional ketosis) gives you greater health benefits than simply taking exogenous ketones.

So remember to eat a healthy, nutritious Keto diet and supplement with exogenous ketones to get additional benefits.

Nutritional ketosis vs Exogenous ketones:

Exogenous ketones could you give an increased boost in energy

You’ll likely feel a slight energy boost from taking ketone supplements.

Whether you’re taking ketone salts or MCT oil, your body can convert these into usable energy sources quite quickly which is why your energy lifts.

But in the long term, being on a healthy keto diet is still a better option. Eating well will help you regain the ability to use your body’s fat stores as fuel which frees you from the energy spikes and dips of having a glucose-dependent metabolism.

This metabolic flexibility means your body always has a supply of energy available, whether it’s from your fat cells or the foods you eat.

Exogenous ketones could provide greater mental clarity

Ketone supplements could also increase your mental clarity by providing this quick source of energy for your brain cells.

However, the real key to eliminating brain fog is the keto diet.

Lack of available glucose causes brain fog when you’re metabolically inflexible – your brain cells can’t switch to using ketones when there’s a dip in glucose levels.

By regaining the ability to use fat as a fuel source (also called becoming “keto-adapted”) you’ll have a clearer mind without being dependent on anything.

Exogenous ketones could aid in weight loss

It’s possible that taking keto supplements could reduce your appetite.

And feeling less hungry could prevent you from overeating and bingeing on high-carb foods.

But just relying on ketone supplements is not a great option if you’re looking for long-term weight loss especially since your body also needs nutrients as well as exercise, sleep, etc.

For more about losing weight on keto, check out our article here.

Exogenous ketones could have therapeutic benefits

There are a lot of studies being done in this area. From potentially reducing anxiety, managing cancer, and even to help with Alzheimer’s.

While the research isn’t conclusive yet, please note that most of the studies with exogenous ketones revolves around ketone esters and typically involves a keto diet in addition to the supplements.

The BEST Ways to Use Ketone Supplements

Here are main occasions when ketone supplements can be useful:

When you’re experiencing keto flu

It can be tough getting started with keto – as your body adapts to using ketones instead of carbs for energy, you can feel irritable, fatigued and experience headaches. These symptoms are commonly known as keto flu.

Luckily, taking keto supplements can lessen the symptoms and make your transition into a keto lifestyle easier.

As an energy booster if you’re an athlete

Especially if you’re doing endurance exercise, taking ketone supplements can be useful for helping you exercise for longer. By increasing your ketone levels, your body can switch to using ketones after it’s exhausted all the available glucose – helping you keep going for longer without resorting to carb loading.

If you need to raise your blood ketone levels

For example, if you’ve dropped out of ketosis because you ate a meal with too many carbs, using ketone supplements combined with the keto diet could help you get back into ketosis faster.

To boost your brain function

If you need to quickly increase your mental productivity, try taking ketone supplements. It’ll give your brain a quick boost of energy in the morning to keep you focused.

Best Exogenous Ketone Supplements

If you’re ready to try exogenous ketone supplements, then which one should you go for?

Here are a few popular brands:


Pruvit keto options are seemingly unlimited, and the claims they have for their products are pretty incredible. People giving Pruvit keto reviews seem to be pleased with the product as well, giving credence to the company’s claims.

Pruvit claims that when you use their products you can reach nutritional ketosis within one hour. Research does show that use of exogenous ketones can result in a rapid increase in your blood ketone levels.

When it comes to exogenous ketones from Pruvit, there are two options: Pruvit Keto OS and Keto OS Max. Let’s look at both of these now.

Keto OS

Pruvit’s Ketone Operating System is better known as Keto OS or as KETO//OS.

Keto OS is a drink mix that is made with BHB salts (beta-hydroxybutyrate) and MCT oil along with flavoring, stevia, malic acid and in some cases, there is also caffeine.

BHB is a ketone body that provides the human body with energy. When combined with a mineral like potassium, sodium or magnesium BHB is easily absorbed by the human body.

The MCT oil in Keto OS helps to slow digestion, but it is also absorbed by the liver and converted into ketones.

When BHB and MCT oil are combined, they have been shown to raise blood ketone levels even if there had been no change in diet.

Keto OS comes in three flavors:

  • Orange Dream Charged
  • Orange Dream Caffeine Free
  • Chocolate Swirl Charged

When it comes to Keto OS reviews, they are mostly positive with the only common thread of negativity being that they are priced high.

You should know that the 3.0 blends of Keto OS do not contain MCT oil, but they do offer amino acid, fiber and other digestive aids.

Keto Max

The other popular product from Pruvit is their Keto Max exogenous ketone supplement.

Keto OS Max contains a newer blend of BHB salts than what is found in the original Keto OS product. Pruvit says that this new blend allows for faster absorption allowing you to experience ketosis even sooner.

Keto Max doesn’t offer the benefits of MCT oil or digestive fibers, but it does contain amino acids in the form of L-Taurine and Fermented L-Leucine. There is also flavoring, erythritol and stevia, caffeine and natural coloring in some options.

Keto OS Max comes in several flavors, including:

  • Splash Charged or Caffeine Free
  • Raspberry Lemon Charged or Caffeine Free
  • Swiss Cacao Charged or Caffeine Free
  • Maui Punch Charged or Caffeine Free

You can order both Keto OS and Keto OS Max for a one-time shipment, or you can subscribe to shipments and get your exogenous ketone supplements delivered monthly.

Keto OS Dangers

There are no real dangers to using exogenous ketones like those found in Keto OS or Keto OS Max, but you can definitely expect to experience typical Keto Flu symptoms.

You might experience digestive issues like upset stomach, gas or diarrhea (though the options with MCT oil can help to alleviate this problem).

Bad breath is another often experienced side effect to utilizing exogenous ketones, as elevated ketone levels can cause “keto breath.”

There hasn’t been a lot of long-term research done of the effects of exogenous ketone supplements, especially when the person using them isn’t following a keto diet as they should.

Drs. Phinney and Volek add, “[In] nutritional ketosis the liver makes a steady supply of ketones and continuously releases them into the circulation. In contrast, most ketone supplement protocols involve bolus intakes that don’t mimic the endogenous release pattern. The extent to which this impacts metabolic and signaling responses across different tissues remains unclear.”

If you are willing to put in the necessary work to get the results of a keto diet, you shouldn’t need to use exogenous ketone supplements, but if you do, at least you know where to start.

Ready to start the Keto diet…?

Exogenous ketones can be a great addition to the Keto diet. But please remember that entering nutritional ketosis through your diet is much more beneficial than just using exogenous ketones.

If you’re ready to start eating a Keto diet, then check out our getting started article here.


Louise co-founded Louise's Foods, Paleo Living Magazine, Nourishing Brands, & CoBionic. She has considerable research experience but enjoys creating products and articles that help move people just a little bit closer toward a healthy life they love.