Do Ketone Supplements (Exogenous Ketones) Work?

Do Ketone Supplements (Exogenous Ketones) Work?

Sticking with a long-term diet that’s ultra low in carbohydrates is challenging for many people. Taking ketone supplements is one way to cheat and get into fat-burning ketosis mode. But are exogenous ketones safe and effective? 

Is there a way to have your cake, and eat your ketones, too? Ketone supplements promise to make it very easy to achieve ketosis—the metabolic state where blood glucose levels are so low that the body burns stored fatty acids called ketone bodies. 

Although everybody is biochemically unique, in general, in order to achieve ketosis, you need to limit net grams of carbohydrates to approximately 25 per day. To know whether or not you are in ketosis requires frequent testing with ketone test strips. 

But what if maintaining a super low-carb diet proves too difficult? Should you consider taking ketone supplements? Do exogenous ketones allow people to eat all the carbs they want but still offer all the potential health benefits of following a ketogenic diet such as lower body fat and sharper mental cognition and focus? 

What Are Ketone Supplements? 

Exogenous (outside the body; the opposite of endogenous ketone fatty acids made by the liver) ketones are most often in powder form. These powders are salt-based, containing one of the three primary ketone bodies called beta-hydroxybutyrate or BHB.

BHB is the primary ketone body in ketone supplements because it is chemically stable and thought to be a superior fat-burning ketone body in comparison to acetoacetate and acetone.

If you come across a ketone supplement that’s made not from salt but from ester, don’t take it. That’s because ketone ester drinks, after being available on the market for several years now, still taste really bad.

Another reason to skip ketone ester drinks? A study published in Regulatory Toxicology and Pharmacology said that the milk-based ketone supplement caused “gastrointestinal effects.” (Gurgle. Gurgle.) Still, the researchers concluded, “ingestion of [BHB]  is a safe and simple method to elevate blood ketone levels, compared with the inconvenience of preparing and consuming a ketogenic diet.”

The study also referenced some interesting keto facts: The liver of healthy adults is capable of producing up to 185 grams of ketones per day. Ketone bodies account for 2–6% of an individual’s energy needs following an overnight fast and approximately 40% of energy needs following a 3-day fast.

Ketone esters, also known as raw ketones, seem to be able to kickstart ketosis more quickly than ketone salts. Another advantage is that there is more published research on ketone esters than salt-based ketone supplements. On the flip side, however, besides the awful taste of ketone esters is the steep cost. Just a few servings of the most popular ketone ester products on the market can cost $100.

Do Ketone Supplements Last Long?

With apologies to erectile dysfunction pill commercials, if ketosis lasts longer than 24 hours, call your doctor? Actually, wouldn’t it be great if you could eat all the carbs you want and just take a ketosis supplement and stay in ketosis for days?

Well, therein lies the rub with exogenous ketones. They simply don’t keep you in ketosis as long as eating a traditional ketogenic diet. In one study published in Frontiers in Physiology, three randomized trials were conducted, involving ketone esters and ketone salts. Both drinks elevated blood concentrations of BHB. But their baseline levels of BHB returned to normal after just 3-4 hours.

In the study, ketone salts were found to contain 50% of a particular type of BHB called L-BHB isoform. This form of BHB remained elevated in the blood for 8 hours. That may seem like good news for keto cheaters who are thinking about taking a ketone supplement. However, the L-isoform is eliminated slowly in the urine and does not contribute significantly to the biological activity of ketone precursors as an energy source, explains this research in Frontiers in Nutrition.

Research, by and large, shows that while ketone supplements “are a practical, efficacious way to achieve ketosis,” according to one article written by a biohacking team who experimented with ketone powders, the ketone supplements they tried only raised blood ketones levels by an average of 0.33 mmol/L. This amount is very small.

The biohackers also claim that the ketones actually decreased exercise performance and had no noticeable effect on mental performance, two of the biggest purported advantages of  maintaining ketosis through a low-carb diet.


Following a ketogenic diet takes discipline. It’s not for everybody to do it day in and day out. If you have the money—and don’t mind the dubious taste and possible digestive disturbances—then taking a keto supplement every now and then may help raise ketone fatty acid levels in your body. This could be especially useful if you need a carb cheat day.

Like anything else, if it sounds too good to be true, it probably is. Taking keto supplements may sound appealing but sticking to a low-carb diet is probably better for maintaining ketosis for the long-term.

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