Edited from HVMN by Justin Liau and Nate Martins.

Exogenous ketones come from a synthetic source–they are not produced in the body. Those are endogenous ketones, produced by the body during fasting, or while following a ketogenic diet–but this can take weeks or months.

With the advent of exogenous ketones, scientists have developed a way to raise ketone levels significantly and safely without the need to fast or diet.

Emerging research shows moderate levels of ketones can increase health and performance.

Exogenous ketones provide the body with another fuel to employ. Think about it like an electric car that runs on both gas and electricity: by consuming ketones along with carbohydrates, the body will preferentially burn the ketones first, saving the carbohydrates for later. Exogenous ketones allow us to enter a metabolic state that wouldn't occur naturally: the state of having full carbohydrate stores, as well as elevated ketones in the blood. This could be advantageous to athletes looking to boost their physical performance.

Consuming exogenous ketones isn't the same as following a ketogenic diet–the ketones in the blood haven't been naturally produced by the breakdown of fat stores. However, scientists believe many of the health benefits of the keto diet and fasting (aside from weight loss) are triggered by ketones. Therefore, raising ketone levels through either endogenous or exogenous ketosis could help to improve health and performance by:

• Reducing inflammation: ketones reduce activation of inflammatory processes1
  
  

• Reducing oxidative stress: ketones scavenge harmful reactive oxygen species2
  
  

• Metabolic flexibility: Affecting gene expression and cellular processes associated with brain health and longevity
  
  

Disadvantages

• Ketone salts can cause gastrointestinal issues, especially at high doses
  
  

• Most ketone salts are a mixture of the two optical isoforms of BHB (D- and L-). Human metabolism of L-BHB has not been studied, although it does not appear to be metabolized as rapidly as D-BHB5
  
  

• Many of the ketone salts currently available are not considered FDA GRAS (generally regarded as safe)

Choosing an Exogenous Ketone

When considering ketone supplements, it's imperative to consider:

• The impact on blood ketone levels and the resulting level of ketosis
  
  

• The quality of the supplement and what impurities it may contain (like sugar, MCT powder or caffeine)
  
  

• The importance of your overall experience. Do you care about price, taste, side effects, etc.?
  
  

Exogenous ketones are a new and exciting technology. They may give some of the benefits of ketosis without having to follow a ketogenic diet to trigger ketone production. Further research is required to fully understand how exogenous ketones affect performance, recovery and cognitive ability–but the early results are promising.

Scientific Citations