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What Are Exogenous Ketones?

Published on: September 25, 2018

What Are Exogenous Ketones?

With the keto diet rapidly growing in popularity, there's also a rising number of keto supplements emerging on the market. One of the latest you may have noticed are exogenous ketones. These supplements can help you ease into the keto diet and provide a plethora of other benefits as well.

Exogenous ketones have been introduced fairly recently, in 2014 to be exact, but there's already a substantial number of studies proving their safety and efficiency. Still, if you're having doubts about these revolutionary keto supplements or simply want to learn more about them, we're here to help you out.

In this article, you'll find out what these supplements are, how they work, and what research has to say about them so far. You'll also learn how you can and should use them on your keto diet and if they're really worth your time and money. But first, let's start by explaining what ketones are.

About Ketones

Ketones, aka ketone bodies, are water-soluble molecules your liver makes as an alternative fuel to glucose. Our cells normally run on glucose while the brain is completely reliant on it. To help you thrive and survive in times of low glucose availability (like during illness or starvation for example), your liver starts to break down fatty acids to make three types of ketones:

  • Acetoacetate
  • β-hydroxybutyrate
  • Acetone

Of these three, β-hydroxybutyrate is the most abundant of the three and the ketone most commonly found in exogenous ketone supplements. When ketone blood levels increase and when most of your body's energy comes from ketones, you are in a metabolic state called ketosis.

Although ketosis is different from your body's usual state of burning sugar for fuel, it is completely normal and healthy even [1]. Your body is also perfectly adapted to keep blood ketone levels within a normal range with the help of insulin. But if your body has trouble making insulin (type I diabetes), then your body may struggle controlling ketone production which then can reach unhealthy levels (ketoacidosis).

Being in ketosis comes with a wide range of benefits such as:

  • Increased mental focus – ketones protect the brain against oxidative stress [2] and are a more efficient energy source than glucose [3] which boosts mental functioning.
  • Balanced blood sugar – Studies show that keto diets have the potential to reduce blood sugar in type II diabetes [4].
  • Aid weight loss – When your body makes ketones, it means that it's burning fat for fuel. Ketones also have an appetite-suppressing effect which also helps you lose weight [5].

To encourage ketosis, people go on a keto diet, fast for long periods of time, or take exogenous ketones. However, exogenous ketones don't really put you in a state of ketosis the same way a ketogenic diet does. We'll talk in depth about their effects on ketosis in the following lines.

What Are Exogenous Ketones?

The ketones your body makes are called endogenous while those made outside your body are exogenous. Exogenous ketones are created in the laboratory and are used as dietary supplements. There are two classes of exogenous ketone supplements:

1. Ketone salts

Ketone salts are synthetic ketone molecules combined with minerals like sodium, potassium, magnesium, or calcium for easy absorption. They're the most common exogenous ketones you'll find on the market thanks to their mild taste and easy digestibility.

2. Ketone esters

Ketone esters are ketones linked to an alcohol group for easy metabolizing. These were the first exogenous ketones ever made, but their unpleasant taste makes them difficult to market. One of their major advantages is that they can raise ketones to greater levels than salts. Most studies on exogenous ketones today are done using ketone esters.

Most exogenous ketone supplements contain β-hydroxybutyrate (BHB) as the main active ingredient. In your body, BHB is also the ketone most easily detected your blood and the one that's most metabolically active. That's why it makes perfect sense to use it in making exogenous ketones.

Exogenous Ketones Benefits

There are many benefits from taking exogenous ketones. Research is just beginning to unveil their full potential, but here's what we know so far:

Increased Ketone Concentrations

Studies show that taking exogenous ketones increases blood ketone levels for up to 8 hours [6]. And this effect is the same whether you're on a keto diet or not. What that means is that exogenous ketones put you into nutritional ketosis.

Lower Blood Glucose Levels

Animal studies show that exogenous ketones lower blood glucose [7], and researchers are now looking into the therapeutic potential of these supplements in managing diabetes [8]. The way these supplements work in lowering blood sugar levels despite adequate carb intake has to do with the fact that they suppress gluconeogenesis. Gluconeogenesis is a metabolic process in which the body makes glucose from protein.

Appetite Control

A recent study found that ketone drinks lower ghrelin, the hunger hormone [9]. Ketones also affect the levels of cholecystokinin, which is a hormone that acts as a hunger suppressant.

Treating the Keto Flu

One of the most commonly sought-after use of exogenous ketones is as a keto flu remedy. Ketoers experience the keto flu when they're just beginning to transition into ketosis. Studies show that taking exogenous ketones can reduce keto flu symptoms [10]. On the downside, the same studies suggest that exogenous ketones suppress ketone production in the liver, so it may take you longer to transition into ketosis when taking these supplements.

Brain Health

The keto diet was originally designed as a treatment for a brain condition called epilepsy. That's because researchers noticed that ketones have a positive impact on the brain, helping reduce seizures, slow down Alzheimer's, increase recovery following brain injury [11]. Because ketones boost brain health, you'll notice better memory and improved focus when taking exogenous ketones.

Lowering Inflammation

Exogenous ketones can also improve your overall health by lowering inflammation [12]. Researchers believe that chronic inflammation is the leading driver of many diseases [13]. By lowering inflammation, exogenous ketones can help prevent cancer, autoimmune disorders, neurological conditions, and metabolic diseases.

There's also evidence that ketones reduce anxiety and improve exercise performance and recovery [10]. Following the keto diet is the best way to get all these health benefits, but exogenous ketones can provide a helping hand when you're struggling to maintain ketosis.

Exogenous Ketones vs. Nutritional Ketosis

While exogenous ketones boost ketone levels in the blood, they don't affect your metabolism the same way ketosis from a keto diet does. These products are supplements and not a replacement for a varied ketogenic diet. If you've ever considered taking them as a shortcut to achieve long-term ketosis, you'll be disappointed to learn that that's not what exogenous ketones are about.

When you follow the ketogenic diet, a complex set of metabolic changes and adaptations takes place in your body. First, your blood glucose along with your liver glycogen levels drop. Secondly, glucagon stimulates the release of fatty acids from fat tissue which are converted to ketones in liver mitochondria. Lastly, the brain starts using most of the ketones produced while blood sugar levels remain at a low, but healthy level.

But when you take exogenous ketones, your body does not break down fatty acids to make ketones. In fact, taking these supplements can prevent or slow down ketosis. These supplements do, however, lower blood glucose levels for a period of time and their presence in the blood mimics nutritional ketosis.

The biggest difference between taking exogenous ketones and being on a keto diet has to do with sustainability. On a keto diet, you can maintain ketosis indefinitely. When taking exogenous ketones, you'll be in ketosis until your daily dose wears off and nobody can guarantee you that you're burning fat while taking these supplements.

Why Use Exogenous Ketones?

Since exogenous ketones can't really compare to true nutritional ketosis, you may be wondering why you should use them in the first place. Well, exogenous ketones help boost your success with the keto diet and can also have a huge impact on your workouts. Here are a couple of reasons you may want to consider taking these supplements:

To Treat the Keto Flu

We already mentioned that exogenous ketones help fight the keto flu. They provide an almost instant supply of energy and they also trick your body into thinking it's already in ketosis. Exogenous ketones can also prevent electrolyte imbalances – the leading cause of keto flu symptoms. This is especially true for ketone salts that contain important electrolytes like sodium and magnesium.

To Correct Diet Mistakes

The keto diet can be hard to maintain, especially for beginners. It's quite easy to go overboard with the carbs since many are hidden in common foods. If you accidentally go overboard with the carbs, taking exogenous ketones will prevent you from being kicked out of ketosis.

For Better Workout

Ketones act as fuel during workouts and even alter the way your body uses other fuel sources.

Studies show that your muscles oxidize ketones when you exercise, that ketone levels rise following workouts, and that trained muscles are more efficient at utilizing ketones [14]. Ketones also attenuate the breakdown of muscle proteins post workout. But most importantly, having high levels ketones slows down glycogen depletion in skeletal muscles which helps athletes exercise for longer.

To Boost Weight Loss

Exogenous ketones can help you on your weight-loss journey by lowering your appetite and through ketosis. As already mentioned, they also give you extra energy for intense workouts which definitely helps with weight loss. However, they're not a magic pill that can make you lose weight without lifting a finger. You need to follow a calorie-restricted keto diet and exercise regularly in order to lose weight.

For Brain Power

If you're looking for a nootropic to boost your focus and memory, then exogenous ketones may do the trick. Your brain is a power-hungry organ, consuming up to 20% of your body's energy. Ketones being an efficient energy source boost brain functioning through adequate energy supply. Also, without blood glucose fluctuations giving you brain fog [15], you can expect more productive days with exogenous ketones.

Are Exogenous Ketones Safe?

As is always the case with supplements, safety is a major concern, especially when you're dealing with novel products like exogenous ketones. Unfortunately, research in this area is limited and we'll need to wait for more studies to confirm that exogenous ketones are completely safe.

But for now, researchers did check the safety and tolerability of exogenous ketones and most studies show positive outcomes [16,17]. Study participants would have a healthy rise in blood ketone levels (around 2 mM) and they were able to tolerate exogenous ketones well. That's because a healthy body can remove any excess ketones through breath and urine, so chances of toxicity are pretty low even when you take your ketones orally.

When it comes to side effects, exogenous ketones can cause minor problems when not taken correctly. Nausea and constipation can happen if you take more than the recommended daily limit or if you take exogenous ketones too frequently.

Just like endogenous ketones, exogenous ketones can also have a diuretic effect making you lose electrolytes. This is easy to prevent by simply drinking enough fluids and replenishing your electrolytes when needed.

How Do You Take Them?

Most exogenous ketone supplements come in liquid or powder form. Some need to be dissolved in water while others are taken as is. But whatever the case, make sure t follow packaging directions and stick to daily limits for best results.

If you want to take exogenous ketones for their cognitive benefits, then having a dose early in the morning works best. Add the ketones to a glass of water or even your morning coffee. You'll have an almost instant supply of energy for the next 3-4 hours or even 8 if you're lucky.

If, however, you're planning to use these supplements for your workouts, then we suggest taking the maximum daily dose 20 minutes before or after your workouts. Taking them before will give you a boost of energy for better performance while taking them after a workout spares muscle glycogen and protein.

And where weight loss is your main concern, exogenous ketones are best taken before a meal. They help suppress your appetite making you eat less. Still, make sure that you're eating enough fats and protein to maintain good health and stay in ketosis. Undereating can cause problems in the long run. To know how much of each macro you need to take in when trying to lose weight on a keto diet, use our Keto Calculator.

Are Exogenous Ketones Necessary?

In a nutshell, no. Exogenous ketones are not an indispensable part of going keto. They're simply a supplement that makes keto dieting easier and/or more convenient.

If you decide to add them to your keto diet, keep in mind though that exogenous ketones can help you when you're experiencing:

  • Weight-loss stalling
  • Fatigue or mental exhaustion
  • The keto flu
  • Poor workout recovery
  • Poor exercise performance

If you're doing fine on your keto diet and are not experiencing any trouble whatsoever, then you likely don't need exogenous ketones. Still, they're good to have around just in case you go through a trying period on your keto diet.

Keep in mind though that exogenous ketones are a bit pricey. This is especially true for ketone esters. Sourcing, purifying, and isolating BHB is a laborious and lengthy process and most sellers use proprietary ingredients so do expect a hefty price tag.


Exogenous ketones are currently a big hit in the keto community. These novel supplements help keto dieters boost their BHB levels, suppress appetite, and enhance workouts. They're considered safe and most people tolerate them well.

However, exogenous ketones are not a substitute for low-carb eating. Although they do put you in a state of artificial ketosis, they don't provide the full range of benefits of a ketogenic diet. Your chances of weight loss and better overall health are really low if you rely only and solely on exogenous ketones.

But as an addition to a well-balanced keto diet, exogenous ketones can work wonders. If you're ready to splurge on these popular supplements, then expect to see your progress improve even more.


  1. Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. 2013 June 26 -
  2. Greco T, Glenn TC, Hovda DA, Prins ML. Ketogenic diet decreases oxidative stress and improves mitochondrial... View all references

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