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Exogenous Ketones: Will They Help You Lose Weight?

By Fitoru | 19 June 2019
keto foods and exogenous ketones

Ketones are the key to turning body fat into energy, and they’re what people are after when they begin a ketogenic diet. The keto diet is a low-carb, moderate-protein, high-fat diet, designed to retrain the body to burn fat for energy instead of the easy-to-digest sugar in carbohydrates. Switching the body into producing its own ketones, however, can be a bit of an ordeal, and can involve physical symptoms collectively known as “keto flu.” Supplementing with ketones is thought to be a way to speed up the process, but does it? Do exogenous ketones help you lose weight, with or without a keto diet? This article provides the answers.

What Happens During Ketosis?

After a few days of keeping a keto diet, your body enters a state of ketosis, which is characterized by quick weight loss and elevated blood ketone levels. When your body is denied carbs, it’s then unable to rely on glucose (sugar) for its fuel source, and instead turns to the fats you eat for energy, and then the fat stored on your body. Breaking down fats for fuel is the process that produces this other energy source, ketone bodies, and this new metabolic state is known as ketosis.

You’ve actually probably been in small states of ketosis before, like if you’ve ever fasted, or during periods of high-intensity exercise performance

There are two main types of ketone bodies that get produced in this state, acetoacetate and beta-hydroxybutyrate, with the ketone body acetone coming in third. They are the energy molecules that replace glucose and keep you going with fuel from fat instead of sugar. Some researchers speculate that the ketone bodies are specifically responsible for ketogenic weight loss.

Why Take Exogenous Ketones? What Are They?

Ketone bodies can enter your bloodstream in two ways: either your body produces them in-house by burning fat (endogenous ketones), or your body receives synthetic ketones from an outside source (exogenous ketones). That means that all ketone supplements are classified as exogenous (the endogenous ones are unique to you and you alone).

For example, you will not be able to get the ketone body acetoacetate from a supplement, as it doesn’t have a stable enough chemical structure to be produced as a supplement. However the ketone beta-hydroxybutyrate (BHB) does, and can be purchased if you’re seeking ketone body supplementation. 

The two most popular forms of ketone supplementation are:

  • BHB ketone salts: Easily found in powdered form, these products contain ketones bound to salts like calcium, potassium, magnesium, and sodium.
  • BHB ketone estersLess easily found than ketone salts, ketone esters are often sold in liquid form, and contain ketones bound to esters, which are chemical compounds created by replacing hydrogen atoms with other molecular groups (a lot of naturally occurring essential oils are esters of fatty acids, for example).

Each of these supplement forms have been shown to increase levels of blood ketones in the body, with a recent 2018 study demonstrating that about 12 grams of ketone salt supplements increased blood ketone levels in human subjects by 300%. This is nearly equivalent to the effects of the ketogenic diet on ketone blood levels, but the question remains: does the intake of exogenous ketones have the same weight-loss effect?

Can exogenous ketones help you lose weight?

Exogenous Ketones: Benefits and Drawbacks

Exogenous ketone supplements are taken either by those beginning a keto diet who want to reach ketosis as quickly as possible with minimal keto flu symptoms (bad breath, headache, digestive issues, and/or muscle cramps), or by those who want to get ketones without necessarily following a strict keto diet (like athletes who still need their carbs). How well have they been proven to work in either scenario? What are the health benefits vs. the drawbacks of exogenous ketones? See the scientific findings below to find out.

Pro: Appetite Suppression and Athletic Performance

Exogenous ketones have shown some potential for decreasing appetite, leading to less calorie intake and greater weight loss. Findings from a 2018 clinical study suggest that a ketone ester drink can help reduce the “hunger hormone” ghrelin and contribute to appetite suppression. Researchers calculated that the participants taking the ketone ester reported 50% less hunger than those drinking a sugary drink after an overnight fast.

Diet is still a large factor in results such as these, as evidenced in a 2017 study that showed that those who ate a meal before exogenous ketone supplementation experienced less of an impact on ketone levels. Nonetheless, researchers concluded that “exogenous ketone drinks are a practical, efficacious way to achieve ketosis.” 

These results suggest that exogenous ketones are most effective during fasting (first thing in the morning) than they are after a meal containing carbs, though they increase ketone levels post-carb consumption too. 

Studies also show that athletes who cannot adhere to an extremely low-carb diet can still enjoy the benefits of ketosis with the help of exogenous ketone salts and esters to improve athletic performance and mental clarity.

Con: Calorie Content, Cost, and Possible Fat-Burning Inhibition

Because exogenous ketones are a fuel source, they come with calories, about the same amount per gram as carbs and protein. While one serving of ketone salts usually has fewer than 100 calories, you’d need several servings per day to help maintain ketosis. Exogenous ketones only last for a few hours before you need to replenish, unlike the endogenous ketones your body makes when in ketosis. 

Then there’s the cost. At about $3 per serving, using exogenous ketones indefinitely instead of adjusting your diet can be quite costly.

Not only that, if you’re giving your body exogenous ketones for “free,” your body may start to use them as a crutch. The reason our bodies burn sugar before fat is because it’s easier, and while BHB salts and esters are indeed effective for periods of fasting and entering ketosis, the higher your levels of blood ketones, the less your body understands it needs to produce them, meaning it’s not burning fat to get its own endogenous ketones, because it’s being handed exogenous ketones instead. This could help you maintain your weight, but excessive exogenous supplementation could inhibit the fat-burning effect and weight loss so remarkable with the keto diet. 

Additionally, blood ketone levels can sometimes get too high, especially when the ketones are coming from an outside, artificial source. This could cause your blood to become acidic, so purchasing a blood ketone meter is a good idea to help keep track of your levels and know when you’re close to being in or out of ketosis.

Exogenous Ketones: Side Effects

Taking exogenous ketone supplements is a safe way to increase your blood levels of ketone bodies, but some people have reported side effects, such as diarrhea, nausea, and stomach discomfort. Ketone salts also bring with them a hefty dose of minerals, taking up a large percentage of your daily recommended intake of nutrients like magnesium, calcium, and sodium. The keto diet can deplete some of these minerals, so the balance may be a plus, but if you aren’t following a keto diet, it’s important to monitor your mineral levels. 

Choose your products wisely, and keep an eye on their nutritional composition so you don’t go overboard on the salt. This is why it’s recommended not to use BHB salts as your sole road into the state of ketosis, which begs the question: what else is there to help?

Exogenous Ketones vs. MCT Oil

Exogenous ketones are a handy helper to the keto diet, but they aren’t the only keto-approved supplement. 

MCT stands for medium-chain triglycerides, and MCT oils are also supplements used to aid ketosis. Derived from the relevant component in coconut oil, MCT oil or MCT powders provide your body with long-term digestible energy derived from healthy fats, helping those eating a keto diet meet their high-fat requirements more easily. Here are the quick differences between exogenous ketones and MCTs.

Exogenous Ketones Facts

  • Boost energy levels right away
  • Suppress appetite and improve athletic performance
  • Support fasting or accelerate ketosis
  • Heavy with salt and other minerals, plus calories (though no fat)
  • Cannot entirely replace endogenous (self-made) ketones

MCT Oil Facts

  • Provides long-term energy for endurance
  • Naturally suppresses appetite
  • Supports nutrient absorption and endogenic ketone production
  • Contains calories from fat
  • Slower to digest than exogenous ketones (but quicker than food)

If body fat loss and ketosis are what you’re after, use both MCT oil and exogenous ketones to capitalize on their unique strengths. Exogenic BHB ketones can tide you over when fasting (and remember that you’re fasting while you sleep), when entering ketosis, or when trying to maintain ketosis when you just can’t cut carbs so low (for example, athletes like runners and cyclists who need fast energy). MCT oil has you covered when it comes to the long-term maintenance of a ketogenic diet.

Can exogenous ketones help you lose weight?

Exogenous Ketones: Weight Loss and Keto Support

Long story short: do exogenous ketones work? Yes. 

People generally use exogenous BHB supplements to transition into ketosis and to bridge the gaps between fasting and higher carb intake. Exogenous ketones help train your body to use and seek ketones for energy instead of blood glucose. 

You can get exogenous ketone support in both BHB oil capsules or in powdered BHB form to help minimize keto flu symptoms, get into ketosis quicker, and maintain ketosis for longer. Any period of time spent out of ketosis is valuable time lost when you could have been burning fat, and exogenous ketones can help minimize that lost time.

When times are good and you’re comfortably in ketosis, you can supplement with MCT oil softgels to meet your macronutrient requirement for healthy fats and keep your exogenic BHB supplements handy if you ever go over in carbs, just to make sure you body is never without the ketone bodies it needs to keep your body fit and lean.


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