Exogenous Ketones: What Are They and Do They Work?

Endogenous ketones are organic acids released as a by-product of fat-burning when the body is in a metabolic state of ketosis.

In contrast, exogenous ketones are synthetically manufactured ketone bodies widely available as nutritional supplements. 

Here’s the difference between exogenous and endogenous ketones and why synthetic ketone bodies don’t have the same health benefits as those generated during ketosis.

What are ketones?

Ketones, or ketone bodies, are organic acids produced by the liver during ketosis, a metabolic state in which the body burns fat for energy instead of relying on glucose as its primary fuel source.

The breakdown of dietary and stored body fat releases large amounts of ketones, which serve as a highly effective alternative fuel that enters the bloodstream and supplies energy to the body’s tissues and cells.

Acetoacetate and beta-hydroxybutyrate (BHB) are the two most abundant ketones produced during fat-burning, though acetone is another ketone body created during ketosis.

Watch the video below to learn why exogenous ketones may hinder weight loss.

Exogenous ketones vs. endogenous ketones

Ketosis and ketone production can be triggered by fasting routines, including prolonged and intermittent fasting and dietary carbohydrate restriction, such as a low-carb diet. This limits the availability of blood sugar as the primary fuel source and shifts the body into fat-burning mode. 

Ketone bodies naturally produced during ketosis are called endogenous ketones, which are released as the body utilizes fat to generate energy.

Ketones that are synthetically manufactured and obtained through supplementation are referred to as exogenous ketones, which are typically available as ketone salts and ketone esters. 

Ketone salts are produced by binding BHB ketones to mineral salts, such as sodium, calcium, or potassium, while ketone esters are liquid formulations made by chemically bonding BHB ketones with alcohol or glycerol derivatives.

Ketones and weight loss

Ketosis has been found to be a highly effective strategy to achieve sustainable weight loss, which explains why many assume a ketone supplement can promote fat-burning without dietary intervention. 

Endogenous ketones are produced when the body burns fat. This can lead to significant weight loss if dietary fat intake doesn’t exceed the body’s energy needs, allowing the body to utilize stored fat for fuel.

Additionally, ketones have been shown to suppress ghrelin, a hunger-stimulating hormone produced in the stomach. Appetite suppression can help reduce snacking and overeating, which are common contributors to weight gain. 

This has been confirmed by a study published in Obesity, which reported that consumption of a ketone ester drink lowered hunger and the desire to eat by 50 percent one to four hours after ingestion.

While exogenous ketones act as a potential appetite suppressant, they don’t have the same weight-loss effects as endogenous ketone bodies and may, in fact, hinder fat-burning. 

This is likely due to the body prioritizing the use of the readily available exogenous ketones for energy instead of tapping into stored fat reserves.

“Exogenous ketones won’t help you lose weight as they diminish your body’s capacity to generate endogenous ketones,” explains Dr. Berg. “When you take external ketones, your body will use those as fuel instead of releasing naturally occurring ketones.”

In contrast, nutritional ketosis has been shown to promote consistent weight loss of around two pounds weekly. A study published in the Canadian Family Physician also found that a ketogenic diet led to significantly more weight loss than a low-fat diet.

Downsides of exogenous ketones

While exogenous ketone supplements can offer a temporary energy boost, they can trigger gastrointestinal side effects.

Digestive issues, such as diarrhea, constipation, gas, and abdominal pain, are common symptoms associated with taking ketone supplements. 

Regular intake of ketone salts may also cause electrolyte imbalances, which can lead to fatigue, muscle cramps, headaches, and dehydration. 

Unlike nutritional ketosis, which can be maintained by eating fewer than 50 grams of net carbohydrates daily, exogenous ketones don’t trigger ketosis. Instead, they temporarily raise blood ketone levels without inducing the metabolic shift achieved through carbohydrate restriction. 

This means that exogenous ketones don’t offer the same health benefits of nutritional ketosis, including enhanced fat burning, improved metabolic health, and better cognitive function.

Additionally, most exogenous ketone supplements aren’t budget-friendly, making them an impractical and considerably less effective option to promote a healthy body. 

A better way to get into ketosis

The ketogenic diet is a low-carb, moderate-protein, and high-fat diet that induces ketosis naturally by restricting carbohydrate intake to between 20 and 50 grams of net carbs daily. 

Unlike ketone supplements, which temporarily increase blood ketone concentrations, keto pushes the body into ketosis, thereby stimulating the release of endogenous ketones. 

Nutritional ketosis can lead to more significant weight loss, improved energy, and support optimal cognitive function. It’s also more effective at stabilizing blood sugar levels and improving insulin sensitivity, which is associated with a lower risk of obesity, diabetes, and heart disease.

Research published in StatPearls found that “Compared to low-fat diets, the ketogenic diet demonstrated superior outcomes in terms of glycemic control, weight loss, and lipid markers. The ketogenic diet also showed positive effects on insulin resistance, suggesting it can improve metabolic markers independent of weight loss.”

Additionally, intermittent fasting, which involves periods of fasting and time-restricted eating, can boost ketone production due to caloric restriction and the subsequent shift into ketosis.  

Combining intermittent fasting with a nutritious low-carb diet such as Healthy Keto® is an excellent strategy to trigger and maintain ketosis.

While fasting naturally pushes the body into fat-burning, a high-fat diet helps maintain ketosis during your eating windows. This approach not only enhances endogenous ketone production but also supports sustained weight loss and improved metabolic health.

In addition, Healthy Keto focuses on nutrient-rich, high-quality foods, including non-GMO organic vegetables, grass-fed beef, full-fat organic dairy and eggs, and wild-caught fish. This dietary pattern not only supports ketosis but also ensures that you receive essential vitamins, minerals, and healthy fats, contributing to overall well-being and improved health.

Key takeaways

Ketosis has gained popularity for its impressive range of benefits, including weight loss, metabolic health, and improved mental clarity, making exogenous ketone supplements tempting for many dieters. 

While exogenous ketones can serve as an alternative fuel source and increase concentrations of blood ketones, they may actually hinder weight loss, as they limit your body’s capacity to burn body fat.  

In contrast, nutritional ketosis achieved through fasting and a ketogenic diet switches your metabolism to fat-burning, which promotes weight loss and can help reach your health goals more effectively. 

FAQ

1. Do exogenous ketones do anything?

Yes, exogenous ketones can benefit athletes as they offer a quick source of energy. 

However, they’re not as effective for weight loss as endogenous ketones, which are naturally produced during fat-burning when carbohydrate intake is too low to meet the body's energy needs.

2. What is the difference between MCT oil and exogenous ketones?

MCT oil, or medium-chain triglyceride oil, contains naturally occurring saturated fatty acids typically derived from coconuts. MCTs are rapidly absorbed and metabolized into ketones, providing a quick source of energy. 

In contrast, exogenous ketones are synthetically made ketone bodies, which are often taken to raise blood ketone levels but don’t offer the same benefits as endogenous ketones. 

3. What are the different types of exogenous ketones?

The two primary types of exogenous ketones are ketone salts and ketone esters. 

While ketone salts are beta-hydroxybutyrate (BHB) ketones bound to minerals, such as sodium, calcium, or potassium, ketone esters contain BHB ketones stabilized by alcohol or glycerol derivatives. 

4. How long does it take for exogenous ketones to work?

Serum ketone levels have been shown to increase after 30 to 60 minutes of exogenous ketone ingestion. However, the effects of exogenous ketones are short-lived and typically last for a few hours. 

To maintain elevated ketone levels, continuous supplementation is necessary, but doesn’t offer the same sustained metabolic benefits of endogenous ketones produced through a low-carb diet or fasting.

5. Do exogenous ketones work for weight loss?

No, exogenous ketones aren’t the best solution to promote weight loss and may even slow weight loss efforts. This is likely because the body uses supplemental ketones instead of stored body fat to generate energy.

6. What are the side effects of exogenous ketones?

The main side effects of taking an exogenous ketone supplement are digestive issues, including diarrhea, stomach cramps, and constipation. 

Using ketone supplements, such as ketone salts, may also result in electrolyte imbalances, which can lead to muscle cramps, fatigue, and headaches.

Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813183/ 

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371871/ 

3. https://www.ncbi.nlm.nih.gov/books/NBK499830/