Best Exogenous Ketone Supplements (2024 Update)

Ketone supplements — also known as exogenous ketones — have become a popular product within the keto community. Manufacturers promise that these dietary supplements can improve athletic performance, lessen the symptoms of the keto flu, burn fat, reduce food cravings, boost mental clarity and increase energy levels.

But is any of that true? In this article, I’ll explain everything you need to know about ketone supplements, their role in the keto diet, and how I use them to boost my mental and exercise performance even on days that I’m not in nutritional ketosis.

To help you make an informed decision and pick the product that’s right for you and your dietary needs, I have tested most of the following (which are ranked based on my analysis of their ingredients and effectiveness):

1. DeltaG Ketone Performance
2. KetoneAid – KE4 Pro
3. Kenetik – Ketone Drink
4. HVMN – Ketone-IQ
5. Real Ketones – D-BHB Capsules
6. Audacious Nutrition – KETOSTART
7. Perfect Keto – Base

You can click here to jump directly to the reviews of these ketone supplements, or continue reading to learn more about the different types of exogenous ketones.

What Are Ketone Bodies (Ketones)?

To produce energy, the cells in your body require fuel in the form of glucose (from carbohydrates) or ketones (from fatty acids). Many cells can switch back and forth between these two types of fuel, depending on what type of fuel is available at the time.

That capability is called metabolic flexibility, and it’s crucial for optimal health (as I explain in this article).

In nature, the body produces ketones in the absence of dietary carbohydrates to ensure a steady supply of fuel for the cells that don’t require glucose to function. The metabolic state during which the body makes ketones is called ketosis.

However, it’s worth noting that not all of the body’s cells can use ketones for energy. Some require glucose, which is why the body can also make blood glucose from non-carbohydrate sources (e.g., amino acids) if you don’t consume any carbs for an extended period. That process is called gluconeogenesis and is a survival mechanism.

Types of Ketone Bodies

Your body makes three different types of ketones, including:

• Acetoacetate (AcAc)
• β-hydroxybutyrate (BHB)
• Acetone

BHB is the main ketone body that transports energy produced in the liver to the rest of the body. Most consumer ketone meters measure the amount of BHB ketones in the bloodstream as expressed in mmol/L. If you have more than 0.5 mmol/L of D-BHB, you’re in nutritional ketosis.

AcAc is a precursor to BHB (and acetone), and that’s why it’s considered the mother of ketones. But it’s much less stable than BHB and easily converts into acetone, which is excreted via the breath (thus leading to wasted energy). Some of it also ends up in the urine (where it can be measured using test strips).

Acetone is the reason why your breath may smell fruity when you’re in ketosis. That phenomenon is known as “keto breath.” The best way to measure acetone is by using a breath ketone meter. I’ve been using Biosense to track my state of ketosis because it features clinical accuracy and can detect even trace amounts of acetone in my breath.

Note that any ketones your body makes are called endogenous ketones, as opposed to the exogenous ketones that come in form of the supplements.

Exogenous Ketone Salts vs. Esters

Before we dig into the details of each of these products, let’s briefly talk about the metabolism of exogenous ketones in humans.

First, you need to understand that there are several types of exogenous ketone supplements on the market today:

1. Ketone salts (usually in the form of D/L-BHB salts).
2. Ketone esters (usually in the form of a bond between D-BHB and (R)-1,3-butanediol).
3. Non-ethanol alcohols (usually in the form of (R)-1,3-butanediol).
4. A non-bonded combination of D-beta-hydroxybutyric acid and (R)-1,3-butanediol.

The difference between the first two has to do with how the ketone bodies are chemically bound to alcohol or salts.

Salts are much easier to manufacture, which is why most of the exogenous ketone supplements on the market are sold as salts. The problem with salts is that they can lead to stomach cramping and GI irritation, which is why I try to avoid them. However, it’s worth noting that properly formulated ketone salts that contain reasonable amounts of magnesium are much less likely to cause GI upset. Unfortunately, magnesium tolerance varies from person to person. For example, I can easily consume a few hundred milligrams of magnesium while my wife gets soft stools at much lower amounts.

Plus, it’s worth noting that most of the BHB produced endogenously is D-BHB (97-98%), whereas L-BHB accounts for only 2-3% of endogenous BHB. As a result, many people assume that D-BHB is more effective than L-BHB. However, there is emerging evidence that L-BHB has unique anti-inflammatory and brain health benefits, making it worth adding to an exogenous ketone supplement. Unfortunately, consumer-grade blood ketone monitors can’t measure L-BHB, making comparing ketone esters to ketone salts challenging.

In the case of (R)-1,3-butanediol, the liver can convert this alcohol to either AcAc or D-Beta-hydroxybutyrate (D-BHB), similar to certain medium-chain triglycerides (MCTs), such as C8. While (R)-1,3-butanediol isn’t as toxic as ethanol (the chemical in alcoholic beverages), it can give you a buzz, so it might not be suitable for athletes. That said, I consumed a significant amount of butanediol as part of my Hard Ketones review and didn’t notice any cognitive impairment.

Ketone esters have been used in labs and scientific studies for a while, but weren’t available to consumers until recently. The term “ester” refers to a bond of two molecules — in the case of ketones, a bond between D-BHB and (R)-1,3-butanediol. Chemically, an ester is an organic compound made by replacing the hydrogen of an acid with an alkyl or other organic group.

While ketone esters used to be more expensive than their salt-based counterparts, they’ve come down in pricing and are now often less expensive (when you consider the cost per serving) than ketone salts. Plus, ketone esters have one important benefit: they have been scientifically shown to improve exercise performance in endurance athletes.

I should also point out that there are two types of ketone esters available on the market, including mono esters (R-1,3-butanediol-R-3-hydroxybutyrate) and (AcAc) diester (1,3-butanediol acetoacetate diester).

The first mono ester was developed by Oxford University and the National Institutes of Health (NIH) for DARPA as part of a program called “Metabolic Dominance.” The goal was to develop a ketone body to enhance the endurance and performance of U.S. soldiers.

Since then, studies have shown that mono esters are more effective at raising blood ketone levels. As a result, brands have started commercializing exogenous ketone supplements based on the original “Oxford ester.”

One of the brands mentioned in this article (Kenetik) uses a combination of D-BHB and (R)-1,3-butanediol, but without bonding them together (to create an ester). While some critics of this technique argue that such a product is less effective, tests conduced by the American Brain Council suggest a comparable effectiveness to mono esters at raising blood ketone levels.

Now that you know everything you need to know about ketones and ketone supplements, let’s take a look at the top eight products in this category.

Top 7 Ketone Supplements

Below is a list of what I consider the top ketone supplements for a low-carb diet, based on the quality of their natural ingredients and their effectiveness.

However, even if you’re not following a ketogenic diet, some of these exogenous ketone supplements can help you improve your athletic performance and boost mental clarity.

I’ll share below how I leverage exogenous ketones, even on days that I consume moderate amounts of carbohydrates.

1. DeltaG Ketone Performance

DeltaG holds the patent on the original ketone ester developed by Oxford University for the U.S. Department of Defense. In other words, the company has unique access to the purest and highest-quality ketone ester on the market.

DeltaG offers various formulations of its ketone ester, including △G Ketone Performance, △G Tactical, △Gold Ketone Coffee Booster and △H Ketone Health.

For the initial version of this review, I got three bottles of the △G Ketone Performance that I leveraged strategically for the annual Murph Challenge, which is an intense CrossFit workout that includes a one-mile run, 100 pull-ups, 200 pushups, 300 air squats and another one-mile run — all while wearing a 20-pound weighted vest.

To make the workout even more challenging, my buddy and I decided to fast for 48 hours leading up to the workout. I did the same thing two years ago, and I wanted to see if DeltaG could help me improve my performance.

I expected to perform better when fueled by ketones, but I didn’t expect to crush my previous fasted personal record by 10 minutes! Considering that I’m not getting any younger and I don’t work out as much (or as hard) as I did two years ago, I attribute my performance improvement to DeltaG.

Of course, I kept tabs on my breath ketone levels using my Biosense breath ketone meter during the entire experiment and noticed a dramatic and lasting spike in ketones after consuming two bottles (50 grams) of this ketone ester. As you can see in the screenshot below, my ketone levels increased from 18 to 34 aces after I consumed DeltaG at approximately 8 a.m.

On a side note, another thing I really like about DeltaG is that they ship their products in eco-friendly glass bottles that are better for the environment and free of endocrine-disrupting chemicals (as I explained in my article about the dangers of xenoestrogens).

The only downsides to this ketone ester are the taste and the price.

All ketone esters taste like medicine and while DeltaG added some natural, non-caloric sweeteners to improve the taste, the liquid still tastes slightly bitter.

If you look at DeltaG Performance’s price tag, you might think it’s the most expensive product in the lineup. But that’s not the case if you consider that each pack contains 75 grams of ketones. In other words, you pay just over $1 per gram of ketone ester. That’s very reasonable considering the quality, purity and effectiveness of the product.

Shop DeltaG Performance

If you want to give DeltaG a try, make sure to use code MK20 to get 20% off your one-time purchase.

Note that DeltaG is not available on Amazon or other marketplaces.

2. KetoneAid KE4 Pro

KetoneAid’s KE4 Pro is the only other real ketone ester drink I’ve found available on the market. It’s highly concentrated and delivers 2.5 grams of ketone esters per 5 milliliter serving. Considering that ketone esters are the most effective form of exogenous ketones, it’s arguably one of the best products on the market.

Be aware that KE4 does not taste great. KetoneAid’s formula uses a small amount of organic stevia and citric acid to improve the flavor, but there’s only so much that a little bit of sweetener can do.

Of course, the typical serving size of KE4 is 5 to 15 milliliters, so you don’t have to drink a gallon for it to be effective. Plus, you can dilute it with a few ounces of water if you have sensitive taste buds. I wasn’t bothered by the taste at all, but drinking it did remind me of some of the bitter medicines I had when I was a kid.

The good news is that KetoneAid also offers a less-strong-tasting alternative to KE4 called KE1, which combines ketone esters and ketone salts. I tried KE1 and can report that it tastes similar to HVMN’s Ketone-IQ (discussed below).

Overall, I’ve become a huge fan of KetoneAid because their supplements are highly effective and give you excellent bang for your buck.

Get KE4 Pro

You can also purchase KE4 Pro on Amazon, where single bottles are available.

3. Kenetik Ketone Drink

In 2021, I attended the KetoCon conference in Austin, Texas, where I had a chance to try Kenetik. When I took the first sip, I expected the medicine-like taste that I’ve gotten used to from other ketone supplements. But contrary to my expectations, I was blown away by how delicious this drink is.

When I looked at the nutrition facts, I realized that Kenetik’s Ketone Drink uses pure D-beta-hydroxybutyric acid combined with (R)-1,3-butanediol. In other words, the ketones in Kenetik are neither bound to salts nor are they part of an ester.

So how effective is Kenetik at raising blood ketone levels?

Based on a study by the American Brain Council, one serving of Kenetik (10 grams) raised blood BHB levels in participants to 1.5 mmol/L — the same as ketone (mono) esters. In comparison, 10 grams of D-BHB salts increased blood BHB levels to only 0.7 mmol/L.

To find out what impact Kenetik would have on my ketone levels, I drank two bottles within four hours at the conference. Doing so increased my breath ketone levels to 14 ACES (the equivalent of 1.4 mmol/L). Additionally, I felt a noticeable boost in mental clarity and my desire to eat went away (I had been fasting the entire day).

If you combine Kenetik’s effectiveness and taste, you can see why this is one of my favorite exogenous ketone supplements. The only downside is its relatively high price of almost $9 per serving. To make the pricing more palatable, you can sign up for a subscription, which knocks 15% off the purchase price.

Shop Kenetik

To save even more, make sure to use promo code MK15 for an extra 15% discount.

Note that Kenetik is also available as a ketone concentrate that you can drink straight up or mix with sparkling water. The advantage of the concentrate is its relatively low cost per serving of $3.54 with a subscription.

4. HVMN – Ketone-IQ

Ketone-IQ is the recently-launched successor to “Ketone Ester,” a product HVMN specifically developed to help elite athletes improve their performance. It’s one of the few consumer products that delivers ketone bodies as an alcohol (in the form of (R)-1,3-butanediol) rather than as electrolytes (salts).

However, it’s important to understand that Ketone-IQ is not an ester, since it contains only (R)-1,3-butanediol (one half of an ester). As a result, Ketone-IQ is liquid rather than powder, like some of the other products in this review.

I used Ketone-IQ for a few weeks, primarily before intense CrossFit workouts or when I wanted to boost my mental clarity. What I noticed was that taking a shot of Ketone-IQ before a workout improved my endurance, as long as my heart rate remained at 160 bpm or lower.

But if I crossed that 160 bpm threshold, I started fatiguing at the same rate as I would have without a ketone supplement. That’s because, at that point, my body would switch to an energy system that relies predominantly on glucose and glycogen. If I’m low on both, my performance degrades quickly.

The other thing I noticed was a boost in energy and mental clarity, thanks to the fact that the supplement raised both my blood and breath ketone levels (as measured via finger prick test and using my Biosense breath ketone meter).

A clear benefit of Ketone-IQ (and (R)-1,3-butanediol in general) is that its lack of salts reduces the risk of upsetting your stomach, especially if you take the product several times a day.

One of the downsides of Ketone-IQ is that it comes in plastic containers that can leach endocrine-disrupting chemicals into the liquid, much like plastic water bottles do. Additionally, consuming too much Ketone-IQ can give you a buzz (butanediol is an alcohol after all), so it might not be suitable for athletes. I had no issues with one to three shots of Ketone-IQ before workouts but your mileage may vary.

Shop Ketone-IQ

Ketone-IQ is also available on Amazon.

5. Real Ketones – D-BHB Capsules

Real Ketones is one of the few products available that contains only nature-identical D-BHB, as opposed to a DL-BHB mix.

As a result, you get twice the amount of energy-producing BHB (when comparing equal serving sizes) with Real Ketones than with the other powdered products in this review. On the flip side, you get none of the unique anti-inflammatory and brain health benefits L-BHB has to offer.

I also like that Real Ketones offers a caffeinated and non-caffeinated version of its supplement. If you choose the caffeinated version, just don’t mistake the (comparatively strong) stimulating effect of the caffeine with that of the ketones. That’s why I recommend trying the non-caffeinated version first (to see how you respond to the ketones before adding caffeine).

It’s also worth noting that Real Ketones decided to include BHB that is only bound to sodium instead of other (potentially gut-irritating) minerals. As a result, you shouldn’t experience any GI issues — even at higher doses.

From a pricing perspective, Real Ketones costs $0.80 per serving (1.9 grams of D-BHB). That’s reasonable, considering that capsules are usually more expensive than plain powder.

To learn how the cost per gram of D-BHB in Real Ketones capsules compares to other products, check out my side-by-side comparison table below.

Shop Real Ketones

Note that Real Ketones is also available in powdered form for a slightly lower cost per serving, but only with flavors and additional minerals (e.g., magnesium) beyond sodium.

You can also find both versions of Real Ketones on Amazon.

6. Audacious Nutrition – KETOSTART

KETOSTART is arguably one of the best powdered D/L-BHB supplements on the market. It was developed by Csilla Ari, PhD, who is married to neuroscientist Dom D’Agostino, two researchers who have been using exogenous ketones as part of their scientific studies.

Their idea was to bring a ketone supplement to market that would match the quality and efficacy of the ketones they’ve been using in the lab. KETOSTART by Audacious Nutrition, the company run by Dr. Ari, is exactly that.

My wife and I had a chance to try KETOSTART and we both noticed a boost in athletic performance when working out in a fasted state, as well as reduced feelings of hunger.

I should also mention that my wife has a much less sensitive stomach than I do (even though she doesn’t tolerate magnesium as well), and she didn’t feel any of the symptoms (such as bloating) that often accompany ketone salts. On the other hand, I have a relatively sensitive stomach (but higher magnesium tolerance) and noticed some minor discomfort — though much less than what I have experienced after consuming other ketone salt supplements.

What’s great about KETOSTART is that the product is available with or without caffeine. So if your goal is to boost athletic performance during a morning workout, the formula with caffeine might be your best bet. Since I’m also relatively sensitive to caffeine, I stuck with the caffeine-free formula on most days.

As far as the taste of KETOSTART is concerned, I really liked it and thought that the level of sweetness was quite balanced.

Shop KETOSTART

KETOSTART is also available on Amazon.

7. Perfect Keto Base

Perfect Keto’s exogenous ketone base was the first keto supplement I tried when I started a ketogenic diet a few years ago.

What I like about this exogenous ketone base is that it’s plain and simple, and without any “extra” ingredients you might not want. Instead, it contains 11.4 grams of D/L-BHB in the form of electrolytes, such as sodium, magnesium and calcium.

If your body isn’t used to high amounts of magnesium, you might have to start with less than a full serving of this supplement because a single serving has 98% of the daily value of that particular mineral. While magnesium is important, some people experience GI irritation when they consume so much of it in one shot.

Perfect Keto Base has only 20 calories and less than one gram of carbs per serving. While that’s nowhere near enough to kick you out of ketosis, it technically breaks your fast. So be aware of that if you practice intermittent fasting in addition to maintaining a ketogenic diet.

Perfect Keto’s ketone base is available in the following flavors:

• Chocolate
• Strawberry Lemonade
• Vanilla

In addition to the tubs (which are great for use at home), Perfect Keto also offers BHB capsules and single-serving packs (which are great for traveling).

Buy Perfect Keto Base

You can also find Perfect Keto Base on Amazon.

Side-By-Side Comparison

Below is a side-by-side comparison table of all the ketone supplements I tested for this article, including their effectiveness in raising blood D-BHB levels.

Other Ketone Supplements to Consider

Besides the products I’ve listed above, there are a couple of exogenous ketone supplements that readers have asked me about:

• Juvenescence – Metabolic Switch Drink: Juvalabs’s product is a C6 Ketone Di-ester, but in powder form. Each serving contains 12.5 grams of ketones. Unfortunately, this supplement also contains soluble corn fiber, a highly-processed filler that I’m not a fan of.
• Prüvit – KETO//OS: A liquid ketone supplement that contains a 12-gram blend of amino acids and DL-BHB. What I don’t like about this product is its relatively high price per serving ($6.50). Plus, it’s not clear how much BHB each serving contains.

Exogenous Ketones vs. Keto Shakes

Unlike keto meal replacement shakes, exogenous ketone supplements don’t provide sufficient calories to replace a full meal. So if you’re looking for a keto-friendly product that provides liquid calories as opposed to ketones, choose one of those options instead.

However, if you’re looking for a ketone supplement to help you get started on a high-fat diet, or if you’re looking for something that eases the symptoms of the keto flu, exogenous ketone supplements are your best bet.

The problem is that the keto supplement market is flooded with products. Just go to Amazon, search for “exogenous ketones” and you’ll get over 350 results.

As you might expect, not all of those supplements are created equal. While they might each meet some technical standard for keto compatibility, a healthy diet is a way of life, not a means by which to achieve some short-term goal like weight loss.

Because of that, I care deeply about not only the keto compatibility and function of the products I consume, but also about the overall health impact of those products.

As a result, I take into account factors such as the quality of ingredients, the trustworthiness of the brand, the scientific evidence supporting the brand’s claims, and paleo compatibility before purchasing, consuming, reviewing and recommending products.

That’s why I’ve included only a handful of supplement brands in this article. These are the brands and their products that I have used and trust, and that I feel comfortable recommending to family, friends and readers.

Of course, I don’t doubt there are other reputable companies out there that make great products that I might not have heard about. If you’re one of them, shoot me an email and we can chat.

Health Benefits of Exogenous Ketone Supplements

I bet almost everyone who starts on a ketogenic diet tries a ketone supplement at some point. But do you need exogenous ketones? And, if so, what are the benefits? Some people even claim that exogenous ketone supplements are a scam that hurt more than they help.

The idea behind ketone supplements is to deliver the same or similar benefits that you get when your body is in nutritional ketosis.

But what does the scientific evidence say?

The short answer is that exogenous ketones are no replacement for a proper ketogenic lifestyle and a diet that puts your body into nutritional ketosis.

However, exogenous ketones can help by providing the following benefits:

• Improved cognitive performance.
• Extended peak cognitive performance during exercise.
• Increased endurance performance when you supplement with ketone esters.
• Less severe symptoms resulting from the keto flu.
• May treat or improve symptoms of patients with neurological conditions, such as Alzheimer’s disease.
• Can help you skip a meal without a drop in energy levels.

Improved Cognitive Performance

Your brain’s neurons and your heart prefer ketones over glucose as a form of energy. Plus, ketone bodies can easily cross the blood-brain barrier and thus act as an instant and effective source of fuel for your brain.

If you’re already on a ketogenic diet, you’ve probably noticed your improved focus and mental clarity compared to the high-carb diet you might have maintained before.

However, during the first few weeks of starting a ketogenic diet, you might feel everything but on top of your (mental) game. That’s where exogenous ketones can help to provide the fuel you aren’t getting due to other factors.

Extended Peak Cognitive Performance

If you’re an endurance athlete, you know that long races are mentally exhausting. Sometimes, it’s an athlete’s mental strength — as opposed to their physical dominance — that makes the difference between winning and losing.

Ketones can help you maintain your peak cognitive performance for longer, which can give you an edge in a race.

Increased Endurance Performance

Scientists have demonstrated an increase in endurance performance in athletes who supplemented with ketone esters before a competition. Think of it as a pre-workout supplement!

A study by Oxford University has shown that elite cyclists rode over 400 meters further in a 30-minute trial when fueled with carbs and ketone esters. While that 2% increase in performance might be unnoticeable to the average Joe, it makes a huge difference for elite athletes.

Lessens the Symptoms of the Keto Flu

During the first few days and weeks after having started a ketogenic diet, you might feel sluggish, fatigued, and suffer from brain fog — all common symptoms of the keto flu.

The keto flu is usually caused by an electrolyte imbalance, because you’re not taking in enough sodium.

By consuming exogenous ketone supplements in the form of salts, you can help replenish electrolytes and thus lessen your keto flu symptoms. However, you can also accomplish the same thing by just mixing 1-2 teaspoons of salt with warm water and drinking that instead.

You might also experience keto-flu-like symptoms when your brain runs out of fuel (glucose) before your body has become proficient in creating ketones. For such cases, exogenous ketones can help provide the fuel your brain needs.

Lessening the symptoms of the keto flu is one of the primary benefits of exogenous ketones. In fact, that was the reason why I stocked up on a couple of tubs of exogenous ketones before starting the diet.

Liver and Muscle Protection

Studies in rodents have shown that AcAc, one of the three ketone bodies, is used as fuel by macrophages (a special type of cells that act as inflammatory mediators) and can protect liver cells from diet-induced fibrosis and injury.

Additionally, AcAc helps with the proliferation and regeneration of muscle cells, which is why some athletes supplement with ketones to improve their recovery after intense workouts or competitions.

Treatment for Alzheimer’s Disease

The treatment of particular medical conditions isn’t the focus of this article. However, for the sake of completeness, I should mention that exogenous supplementation has been shown to be highly effective in patients with Alzheimer’s disease and other neurological and metabolic conditions — in particular the ones that are caused by a disturbed glucose metabolism due to a lifelong and high intake of carbohydrates.

To learn more about ketones in general, and their potential health benefits, check out the book Ketones, The Fourth Fuel by Travis Christofferson.

Drawbacks of Exogenous Ketone Supplements

Some people think of ketone supplements as a shortcut to ketosis, and as a way to lose weight without adopting a healthy lifestyle.

That doesn’t work over the long term.

When you consume exogenous ketones, your blood ketone levels go up. However, that doesn’t mean that you’re in endogenous ketosis. If you’re not, you forfeit many of the benefits of a ketogenic diet, including expedited weight loss.

However, supplementing with ketones provides your body with energy while suppressing hunger at the same time. As a result, you’ll likely consume fewer calories, which leads to weight loss.

I don’t recommend maintaining a caloric deficit for extended periods because your body will adjust to it and start preserving body fat. That’s counter-productive as far as weight loss is concerned.

However, there is nothing wrong with doing that for a few weeks while making sure you consume nutrient-dense foods (ideally from animal-based sources).

Unfortunately, there aren’t a lot of long-term studies on ketone supplementation available. However, based on my experience, I recommend using ketone supplements during the first few weeks of your keto journey while you dial-in your nutritional needs and fat consumption.

I used exogenous ketones the first week I was on a keto diet, until I figured out my correct fat and salt intake (and to prevent/lessen the symptoms of the keto flu).

Ketone Supplements Side Effects

Ketone supplements are considered to be safe, but there are a handful of side effects that some people experience, including:

• Gastrointestinal problems, such as diarrhea, nausea and stomach discomfort. That’s one of the reasons why I like the products from DeltaG and KetoneAid — they don’t cause any stomach issues even when consumed in higher amounts.
• Breaking your fast. If you practice intermittent fasting (or any other kind of nutritional fasting), you need to be aware that ketone supplements can break your fast (depending on what your fasting goals are). However, I’d argue that being able to extend your fast by consuming a few calories in the form of exogenous ketones has more benefits than completely breaking a fast with a meal but without ketone supplementation.
• Liver damage. Dr. Ari (the scientist behind KETOSTART) told me that “chronic use of ketone esters can cause serious liver damage.” However, I haven’t seen any published scientific evidence confirming that. In fact, a study published in the American Journal of Physiology – Gastrointestinal and Liver Physiology suggests that ketone esters are liver-protective. Dr. Ari mentioned a soon-to-be-published study confirming her warning, and I’ll keep an eye out for it.
• Intoxication. 1,3 butanediol is a mildly narcotic alcohol that can also put pressure on the liver. However, in all my tests, I have yet to experience any sense of intoxication.
• Increase in insulin. Raising your blood ketone levels too much (above ~2 mmol/L) can cause a release of insulin, which can negatively impact endogenous ketone production and prevent fat loss. That’s why it’s important not to over consume ketone esters (which are very effective at raising blood ketone levels).

How I Use Exogenous Ketones

I was on a strict ketogenic diet for several years, before I began re-introducing carbohydrates in 2021. I wish I had leveraged exogenous ketones more extensively during that time, because it would have made the experience significantly more pleasant — especially for longer fasts and intense CrossFit workouts.

I’m still on a relatively low-carbohydrate diet, but I’m no longer in deep ketosis on most days. Despite that, I still strategically leverage exogenous ketone supplements to improve my athletic performance and to boost my mental clarity.

For example, supplementing with (R)-1,3-butanediol or ketone esters before CrossFit workouts has noticeably improved my athletic performance and allowed me to recover quicker — both mentally and physically.

Additionally, I supplement with ketones when I need my brain to work optimally — especially while recording videos for my YouTube channel or writing research-intensive articles for my blog.

If you’ve been in deep ketosis before, you’ve undoubtedly noticed the incredible mental clarity that ketones offer. You can get the same effect with high-quality ketone supplements!

Just be aware that supplementing with exogenous ketones won’t offer any of the fat-burning or weight loss benefits that endogenous ketones offer (unless you leverage exogenous ketones to skip meals and extend your fasts).

Frequently Asked Questions

The Best Ketone Supplements: Final Thoughts

Exogenous ketones can be a beneficial tool to support your ketogenic journey. Just don’t forget that high-quality supplements are meant to supplement an otherwise healthy dietary lifestyle — as opposed to enabling you to take shortcuts.

With that in mind, exogenous ketones are a convenient way to improve your endurance during certain types of exercises, to fuel your brain with energy when you need it, to provide an overall energy boost, and to reduce the symptoms of the keto flu.

I used ketone supplements when I first started on a ketogenic paleo diet to help lessen the symptoms of the keto flu, and I would do it again. After I had been on keto for several months, I stopped using ketone supplements (except for testing new products to review).

These days, I strategically use exogenous ketones before certain workouts and to improve my mental performance.

What’s your experience with exogenous ketones, and what’s your favorite product? Let me know by leaving a comment below!

Michael Kummer

Michael Kummer is a healthy living enthusiast and CrossFit athlete whose goal is to help people achieve optimal health by bridging the gap between ancestral living and the demands of modern society.