You have probably seen posts all over the internet promising weight loss, sports performance, mental clarity and more from using exogenous ketones, but are they safe and will they help you achieve your goals?
First, you may want to understand what exogenous ketones are. “Exogenous” refers to something that is not produced within the body. Alternatively, “endogenous” describes something produced within the body. The liver will naturally produce ketones from fatty acids during extended periods with low blood glucose.¹ Glucose, free fatty acids and ketones are able to supply energy to the mitochondria of cells, which are our aerobic energy powerhouses. But unlike free fatty acids, ketones can cross the blood brain barrier and can be used for energy by the brain cells and the central nervous system. This can be especially important during times of low blood glucose. When there are sufficient levels of ketone bodies in the bloodstream, the body is said to be in “ketosis.”
This ability for ketones to provide energy when glucose levels are low would have been especially important when we could not just go out to any grocery store, fast food restaurant or into our pantry to eat something for energy.
Some benefits, as listed below, have been observed during times when the body is producing its own ketones. This can be done through starvation or nutritional ketosis, which involves reducing insulinogenic foods (carbohydrates and protein) and increasing fat to a level that reduces blood levels of glucose enough that the body believes it needs ketones for fuel.²
Based on these benefits, companies have started to produce synthetic ketones that we ingest in order to increase blood levels of ketones: exogenous ketones. Some manufacturers state that these can be taken to get the body into “ketosis” without any modification to diet. But that means that if a person were to use these exogenous ketones while still eating the Standard American Diet (SAD), he would have both glucose in his blood, as well ketones. This is not a natural state and the glucose in the blood is still going to cause an insulin spike.
If the idea of ketosis is to retrain the body to use ketones for energy, artificially supplying ketones will not aid in this goal. In addition, we are looking for long-term improvements through dietary and lifestyle changes. Popping a pill or drinking a supplement without other changes is not a long-term solution.
Additionally, supplemental ketones are generally very high in sodium and potassium, which may not be healthy for everyone and can cause blood pressure issues, especially when taken numerous times per day.³
Purported benefits of exogenous ketones:
· Weight Loss – One exogenous ketone supplier claimed that exogenous ketones can lead to weight loss, but no studies were provided to back this up. The vendor's website only provided studies showing that endogenous ketones helped with weight loss (obviously as they are made from fatty acids so stored body fat is broken down to make them), quickly jumping to the conclusion that the two must lead to the same results. Two of the experts on using ketogenic diets for health state that exogenous ketones have not been proven to help with weight loss. ⁴ Additionally, several studies show that using exogenous ketones reduced lipolysis (the breakdown of stored fats for energy).⁵
· Provide energy – Exogenous ketones will provide energy, since they are a direct energy source, but if there is also glucose in the bloodstream, insulin will increase, which puts the body into a storage mode, pushing glucose into fat storage.
· Sports performance – One study concluded that there is not enough evidence to support the claim that ketones can support sports performance.⁶ But another study showed that exogenous ketones helped to increase endurance and reduce lactic acid accumulation.⁷ In addition, a third study showed that exogenous ketones can spare glycogen use. But while this may help to sustain longer endurance exercise, it is spared through a reduction in carbohydrate oxidation⁸ possibly compromising higher intensity efforts during the endurance event (i.e. that last kick to pass someone or cross the finish line under a time goal may be at risk). Overall, there is really no consensus on the effects of exogenous ketones on sports performance and more studies are needed. I think it’s also important that studies be done on steady state endurance athletes and athletes that need to constantly move between fat and carbohydrate burning, such as cyclists or mountain bikers.
· Decrease appetite - A recent study found that supplementing with ketone ester lowered the amount of ghrelin, sometimes called the “hunger hormone,” which led to decreased appetite.⁹ Most of the exogenous ketone supplements on the market today are ketone salts, not ketone esters. Ketone esters are raw ketones that enter the bloodstream more quickly than ketone salts, which elicits a quicker response but the esters taste pretty bad and can lead to GI distress. For that reason, most of the exogenous ketone supplements on the market are ketone salts.
· Improved mental clarity - Some people report better mental clarity and energy but most reports like this are anecdotal and there are few studies that point to proof of these types of benefits.¹⁰
Despite all this, there are times that exogenous ketones can be beneficial:
· They can help with energy when a person is transitioning from a higher carbohydrate diet to nutritional ketosis. Exogenous ketones have been found to help avoid the “keto flu.”
· They can help for some additional mental clarity if used in conjunction with a lower carbohydrate diet.
· If an athlete is already metabolically flexible (able to burn both carbohydrate and fat efficiently for fuel), exogenous ketones may help with sports performance.
I have experimented with Keto/OS and Perfect Keto. I did not notice any change with Keto/OS but noticed a slight improvement in mental function and reduction in appetite with Perfect Keto. The chocolate sea salt flavor was pretty darn good in my fatty coffee.
Based on what we know about how ketones and glucose function, I don’t feel that these expensive supplements are worth the cost when we can use our bodies to produce ketones in a healthy way using nutritional ketosis.
⁴ https://optimisingnutrition.com/2016/08/08/ how-to-make-endogenous-ketones-at-home/