Exogenous ketones are ketones made outside of the body and consumed as a supplement, in contrast to the ketones that our body produces when following a ketogenic diet. The former doesn’t require you to change what you eat, whereas the latter relies on it. In some cases, they can be used as an alternative to a ketogenic diet (i.e., ketosis plus carbs) or complement a ketogenic diet, depending on your goals.

Exogenous ketones are designed to elevate blood ketones, thereby putting you in a state of nutritional ketosis where ketones not only act as an alternative fuel to glucose, but also induce many beneficial effects in our bodies (more on this in a later blog post).

When following a ketogenic diet the liver produces three primary ketone bodies: beta-hydroxybutyrate (BHB), acetoacetate (AcAc), and acetone, but BHB is the primary ingredient most exogenous ketone supplements use in their formulation. You can measure the concentration of ketones (BHB) in your blood with a blood ketone meter, and this can tell you if the product you took is effective or not.

The two major types of exogenous ketones available today are ketone salts and ketone esters.

Ketone salts contain BHB bound to a mineral ion, usually a balanced electrolyte formulation of sodium, calcium, potassium, and magnesium.

Ketone esters contain BHB typically bound to a ketone precursor, further metabolized to BHB in the liver (two for one).

Ketone esters are able to elevate blood ketone to higher levels and for more extended periods, however, they are not yet widely available, they don’t taste great, and they are relatively expensive. It is also likely that elevating blood ketone levels to too high might not be as beneficial either or not necessary for the desired outcome and might cause unwanted side effects. KETOSTART is a ketone salt mix, because they comprise most products that are commercially available and are surrounded by the most confusion.

Exogenous ketones work in a dose-dependent matter, meaning the more you take, the higher your blood ketone levels. Ideally, a BHB supplement should deliver at least 10g of BHB in a serving. This amount is needed to effectively elevate blood ketone levels in a person of normal body weight and therefore this amount is necessary to do what you were hoping it would do – induce considerable ketosis that also lasts for some time! Some products include much less than this (a few hundred mg-s or just 1g), so you may be wasting your money on something producing a placebo effect at best. Unless you are testing your blood following consumption (which is unlikely), certain companies may be getting away with a dose of BHB that isn’t meaningful.

If the label doesn’t state specifically the amount of BHB included per serving, this is a warning sign.

Depending on each person’s sensitivity and metabolism, beneficial effects can start to happen when blood ketone is elevated. As mentioned above, higher levels might not be needed or will cause unwanted effects.

Also, how quickly can we reach ketosis (how fast will blood ketone levels get elevated) and how long blood ketones will stay elevated in the blood are also dependent on the formulation. Combining MCTs with ketone salts can also extend ketosis. Depending on how rapid and/or how sustained you want your blood ketone level elevated will also influence your decision when buying a product.

R(D) BHB and S(L) BHB are two stereoisomers, called enantiomers, molecules that are mirror images of each other. While R-βHB is the normal product of human metabolism, it is metabolized much faster than S-βHB is. S-βHB is not a normal product of human metabolism, however, it is a transient intermediate of β-oxidation of fatty acids, therefore, administration of the same amount of S-βHB may lead to higher level and more sustained blood levels of S-βHB, compared to similar administration of R-βHB.

Some companies claim that using one or the other form is better, but we think that racemic forms (meaning containing both enantiomers) is the ideal combination. Blood ketone meters measure R-βHB exclusively (not S-βHB, AcAc, or Acetone) therefore, total ketone level may be somewhat underrepresented if we use only a blood ketone meter.

There are several formulations available in different ketone supplements. As mentioned, ketone salts include BHB that is most commonly bound to minerals, and depending on the product, the combination of these minerals may be different. They often provide a balanced blend of sodium, calcium, magnesium and potassium, acting as electrolytes complementing a ketogenic diet nicely. The ratio (or the lack of any of these) might be the key to the best formulation.

It is very important that you as the consumer to know what is in the supplement, which means you should expect that all of the ingredients and their exact amount are listed on the label. If the company is not transparent with their formulas, and are hiding ingredients behind the label of “proprietary blend” or simply not listing them, this raises concern. Try to find a company that you feel is open, honest, and has your best interest in mind.

Some added ingredients may improve the formulation while others may be unnecessary, potentially diluting the product or, worse, be accompanied by their own unwanted side effects (e.g., diarrhea). As we mentioned above, what you want to look for is the transparency of the company stating the exact amount of each ingredients (instead or hiding behind secretive proprietary blends) and well justified and scientifically supported reasons why those ingredients will enhance the claimed effects.

We found that some of the ketone supplements have relatively high carbohydrate content, close to 30% of the supplement’s weight, which should be avoided by those on a strict ketogenic diet trying to consume less than 50g carbs per day….not talking about how it is going to influence efficacy. For us, the ideal ketone supplement should not contain more than 2g of carbohydrates per serving with less than 1g sugar.

Ultimately, you have to enjoy the product you choose, it can’t break the bank, and it needs to be relatively accessible and convenient for you to take, or else none of this matter. These are all part of whether you purchase a product or not. Some products are well overpriced for what they deliver, and the price is not always an indicator of quality; instead, the cost needs to reflect efficacy and enjoyment.

Your decision to buy the product ever again depends on whether you enjoy the product or not! Taste is overlooked, but the truth is, many of these supplements are either not even palatable, too bitter, too sweet, leave weird aftertaste in your mouth or simply just not pleasant enough, which of course, influences whether you will feel like consuming it again or not.

Independently from whether you prefer to buy the products in the store, online or through multilevel “network” marketing, your decision will be influenced by whether the product is hard to access, ship, difficult to find, or served in a style that doesn’t suit your needs (e.g. it is hard to take a huge tub for hiking, so you might prefer to take products sold in sachets).

Some ketone supplements are easier to mix and dissolve faster than others, we do not like when the clumps are still floating around on the top of the drink even after 5min of vigorous stirring. It is also not uncommon for some powdered ketone supplements to harden over time because some of their ingredients are hygroscopic. Meaning your once fluffy powder turns to a tub of rock and no longer mixes nicely in liquid. We definitely do not enjoy when it is almost impossible to scrape out a small/desirable amount of ketone powder, because the whole tub is clumped together.

The most common side effect from ketone supplements is GI distress (e.g. diarrhea). In some cases, you may need to work your way up to a given dose to eliminate these side effects, but if you routinely react poorly to a supplement even at a low dose then likely that product is not for you. This may seem obvious, but you want to choose a supplement that you tolerate well, and this may depend on the specific formulation of the product, on your body’s tolerance level and individual metabolism.

Since it is not feasible for everyone to do extensive testing on themselves to find an effective and quality product, we hope that sharing what we’ve learned through our research can guide you. The ketone supplement you choose should be effective (induce ketosis), affordable, enjoyable, convenient, and ultimately, support your goals.