There are three types of ketones produced when you’re on ketogenic diet: acetoacetate, beta-hydroxybutyrate (BHB), and acetone. The kinds that you’ll find in your supplements are BHB because your body can readily use and absorb them. This means that not all ketones are created equal and there are several different types, each with unique properties that are worth considering when shopping.
I’m getting an increasing number of questions about exogenous ketones. Are they good? Do they work for performance? Is there a dose-response curve? If I’m fasting, can I consume them without “breaking” the fast? Am I in ketosis if my liver isn’t producing ketones, but my BOHB is 1.5 mmol/L after ingesting ketones? Can they “ramp-up” ketogenesis? Are they a “smart drug?” What happens if someone has high levels of both glucose and ketones? Are some products better than others? Salts vs esters? BHB vs AcAc? Can taking exogenous ketones reduce endogenous production on a ketogenic diet? What’s the difference between racemic mixtures, D-form, and L-form? What’s your experience with MCTs and C8?
Exogenous ketones are powerful. They will get you into ketosis whether keto-adapted or not. The benefits of this range from weight loss to sustained mental and physical energy. The benefits are the same as those from nutritional ketosis, however, they’re not a substitute for nutritional ketosis. More on that below before we get into the top 5 exogenous ketones for 2018.
Hi.. I’ve recently started drinking Keto OS Max and have lost about 20 pounds in the past 4 weeks without strictly sticking to the keto diet and have not exercised once. The only issue I have with Keto OS is the price really. I am wondering how the other BHB/MCT products like Ketond and PerfectKeto compare to Keto OS and what product on the market comes closest to the Keto OS recipes beneficial ingredients. TIA
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. 

Blood, urine, plasma, and breath ketone concentrations following mole-matched ketone ester or isocaloric dextrose drinks in fed and fasted subjects (n = 16) at rest. Data from both of the two study visits in each condition (fed and fasted) completed by an individual are included in the analysis. Values are means ± SEM. (A) Blood d-βHB. (B) AUC of blood d-βHB. (C) Urine d-βHB excretion. (D) Plasma acetoacetate (AcAc). (E) Measured breath acetone (ppm = parts per million). (F,G) Mean d-βHB Cmax and difference between βHB Cmax over two visits when subjects separately consumed two ketone ester drinks in both the fed (F) and fasted (G) state. X axis = mean d-βHB Cmax of the 2 visits (mM), Y axis = difference between d-βHB Cmax in each visit. 95% confidence limits are shown as dotted lines. Significance denoted by: *p < 0.05 fed vs. fasted.
Measurements taken included whole blood glucose and BHB (every 5 minutes); VO2 and VCO2 (every 15 seconds); HR (continuous); RQ is calculated as the ratio of VO2 and VCO2. In the video of this post I explain what VO2, VCO2, and RQ tell us about energy expenditure and substrate use—very quickly, RQ typically varies between about 0.7 and 1.0—the closer RQ is to 0.7, the more fat is being oxidized; the reverse is true as RQ approaches 1.0
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We demonstrated that therapeutic ketosis could be induced without dietary (calorie or carbohydrate) restriction and that this acute elevation in blood ketones was significantly correlated with a reduction in blood glucose (Figs. 2, ​,33 and ​and4).4). The BMS ketone supplement did not significantly induce blood hyperketonemia or reduced glucose in the rats. The KE supplemented rats trended towards reduced glucose levels; however, the lower dose of this agent did not lower glucose significantly, as reported previously in acute response of mice [59]. MCTs have previously been shown to elicit a slight hypoglycemic effect by enhancing glucose utilization in both diabetic and non-diabetic patients [86–88]. Kashiwaya et al. demonstrated that both blood glucose and blood insulin decreased by approximately 50 % in rats fed a diet where 30 % of calories from starch were replaced with ketone esters for 14 days, suggesting that ketone supplementation increases insulin sensitivity or reduced hepatic glucose output [89]. This ketone-induced hypoglycemic effect has been previously reported in humans with IV infusions of ketone bodies [90, 91]. Recently, Mikkelsen et al. showed that a small increase in βHB concentration decreases glucose production by 14 % in post-absorptive health males [92]. However, this has not been previously reported with any of the oral exogenous ketone supplements we studied. Ketones are an efficient and sufficient energy substrate for the brain, and will therefore prevent side effects of hypoglycemia when blood levels are elevated and the patient is keto-adapted. This was most famously demonstrated by Owen et al. in 1967 wherein keto-adapted patients (starvation induced therapeutic ketosis) were given 20 IU of insulin. The blood glucose of fasted patients dropped to 1–2 mM, but they exhibited no hypoglycemic symptoms due to brain utilization of ketones for energy [93]. Therefore, ketones maintain brain metabolism and are neuroprotective during severe hypoglycemia. The rats in the MCT group had a correlation of blood ketone and glucose levels at week 4, whereas the combination of BMS + MCT produced a significant hypoglycemic correlation both at baseline and at week 4. No hypoglycemic symptoms were observed in the rats during this study. Insulin levels were not measured in this study; however, future ketone supplementation studies should measure the effects of exogenous ketones on insulin sensitivity with a glucose tolerance test. An increase in insulin sensitivity in combination with our observed hypoglycemic effect has potential therapy implications for glycemic control in T2D [40]. Furthermore, it should be noted that the KE metabolizes to both AcAc and βHB in 1:1 ratio [29]. The ketone monitor used in this study only measures βHB as levels of AcAc are more difficult to measure due to spontaneous decarboxylation to acetone; therefore, the total ketone levels (βHB + AcAc) measured were likely higher, specifically for the KE [14]. Interestingly, the 10 g/kg dose produced a delayed blood βHB peak for ketone supplements MCT and BMS + MCT. The higher dose of the ketogenic supplements elevated blood levels more substantially, and thus reached their maximum blood concentration later due to prolonged metabolic clearance. It must be noted that the dosage used in this study does not translate to human patients, since the metabolic physiology of rats is considerably higher. Future studies will be needed to determine optimal dosing for human patients.
Proper sleep is important for hormone function and repair of the body. Not getting enough sleep is tough on the adrenals and blood sugar regulation. Try to get at least seven hours of sleep per night. If you struggle with quality sleep, create an environment that is conducive for rest. This could be keeping your room cooler, turning off all electronic devices one to two hours before bedtime or using a sleep mask.
I had the chance to interview Dr. Ryan Lowery, Ph.D. about this in person. He performs some (not peer-reviewed) research on different brands of ketone salts and is listed as one of the “specialists” on Prüvit’s website. He suggested that we had perhaps ran the tests too long after the supplements were taken, stating that blood ketones tend to peak at 30 minutes. This is, however, not what Prüvit themselves state in their article on the 59-minute test, or the promise to reach ketosis in 60 minutes on the Kegenix Prime packaging. Plus, do you really want to spend up to $390/month on a product that gives you the benefits of ketosis for half an hour?
Second, take a look back at table 2. Kegenix Prime scored as the “winning brand” for 4 out of the 7 markers tested: mental performance, satiety, mental clarity and energy. Compared to the other supplements, it also scored highest for physical performance, although none of the supplements were listed as a “winner” since the placebo outperformed them all for that marker.

Do you need carbs to train? No. Again this is an anecdote only, but I have done numerous training sessions in a carb deprived state. Heck some of my best training sessions where done in a fasted, carb deprived state. And there are a lot of endurance athletes who are using a ultra-low carb/ketogenic diet and putting up some great times (more on this below).

The “BHB salt” is simply a compound that consists of sodium (Na+), potassium (K+), and the ketone body β-hydroxybutyrate.  In supplements like Pruvit’s Keto OS  these individual components are being held together by ionic bonds; however, when you consume the product, it is absorbed into the blood where it dissociates into free Na+, K+, and BHB since it is a water-based solution.  Thus, consuming the product directly and immediately puts more ketones into your blood.

For the ketone esters, on the other hand, repeated doses of 20-30 grams in any one day may be possible. Thus these products may be able to maintain a modest level of ketonemia without dietary carbohydrate restriction. Thus some of the cardiac and brain fueling benefits may follow, not to mention the epigenetic effects limiting oxidative stress and inflammation. But given the recent observation that administered ketone esters markedly reduce circulating free fatty acids (Myette-Cote 2018) — possibly due to an insulin-tropic effect or direct suppression of lipolysis (Taggart 2005) — their sustained use in people with underlying insulin resistance may compromise their long-term benefits by promoting weight gain unless combined with carbohydrate restriction.
Dominic D’Agostino has two in-depth interviews on The Tim Ferriss Show (Part 1, Part 2). Discussion includes exogenous ketones for mitigating the onset of neurodegenerative diseases, using ketones in place of fasting for chemo-protection, benefits of ketone supplementation when consuming carbohydrates, the risks and potential toxicities of ketones.

Given that blood βHB after identical ketone drinks can be affected by factors such as food or exercise (Cox et al., 2016), the accuracy of tools for non-invasive monitoring of ketosis should be investigated. Breath acetone and urinary ketone measurements provide methods to approximate blood ketosis without repeated blood sampling (Martin and Wick, 1943; Taboulet et al., 2007). However, breath acetone did not change as rapidly as blood βHB following KE and KS drinks. Acetone is a fat-soluble molecule, so may have been sequestered into lipids before being slowly released, resulting in the differences observed here. Similarly, significant differences in blood d-βHB between study conditions were not reflected in the urinary d-βHB elimination. As the amount of d-βHB excreted in the urine (≈0.1–0.5 g) represented ~1.5% of the total consumed (≈23.7 g), it appears that the major fate of exogenous d-βHB was oxidation in peripheral tissues. These results suggest that neither breath acetone nor urinary ketone measurements accurately reflect the rapid changes in blood ketone concentrations after ketone drinks, and that blood measurement should be the preferred method to quantitatively describe ketosis. That said, it should be noted that although commercial handheld monitors are the most practical and widely available tool for measuring blood ketones, they can overestimate blood D-βHB compared to laboratory measures (Guimont et al., 2015) and these monitors do not measure L-βHB and so may not provide accurate total blood ketone concentrations, especially if a racemic ketone salt has been consumed.

Various reasons can motivate you to get into ketosis as part of the Ketogenic Diet. These may range from medical purposes so that you stay healthy, to keeping various ailments away. If you are an athlete, you may get into ketosis to keep your body fit for the upcoming competitions. Some people get into ketosis just to shed some extra fat and keep their bodies in perfect shape. Regardless of the reasons, here are practical tips on how to get into ketosis in 24 hours.

Another source of the D-BOHB isomer is an evolutionarily ancient energy source for micro-organisms. Poly-BOHB is a long chain of D-BOHB molecules strung end-to-end. It functions in many single-cell organisms as a concentrated energy source similar to glycogen in mammals, but whereas glycogen breakdown releases individual glucose molecules, poly-BOHB hydrolysis releases single D-BOHB molecules.
Elliot received his BS in Biochemistry from the University of Minnesota and has been a freelance writer specializing in nutritional and health sciences for the past 5 years. He is thoroughly passionate about exercise, nutrition, and dietary supplementation, especially how they play a role in human health, longevity, and performance. In his free time you can most likely find him lifting weights at the gym or out hiking through the mountains of Colorado. He will also host the upcoming BioKeto podcast. You can connect with him on Facebook ( and Instagram (@eazy_ell)
The Zenwise Keto Life BHB Salt uses a custom calcium, magnesium and sodium ketone complex to help access ketones for fuel without the low carb diet or fasting. This product is another all-natural option that goes as far as using turmeric for its added coloring. It is a proven product with hundreds of happy customers. They seem to have a strong grasp on the lemonade side of the exogenous market with their Raspberry Lemonade and Wild Limeade flavor choices.
Hi all…thanks for your articles and info. I am currently on a paleo diet, but want to lose more weight and bring it up a notch w/ ketogenic diet and be in ketosis. Not sure which product is best? Do you take the MCT oil and also a ketone powder. I know it may be difficult at first, but I am up for the challenge as we start the new year and would like to loose 40 lbs by May/June. Please advise as to what products are best so I can purchase. THANKS

Great question. So if you are already in nutritional ketosis from your diet, exogenous ketones would still help raise ketone (energy) levels when you want that (maybe for focus at work or energy at the gym. They also help get you back into ketosis after cheat meals and skip the “keto flu” which is the period when your body is using up stored glycogen.

I just read your comment and was wondering the same thing. I can see how exogenous ketones can be a great energy boost to people on the ketogenic diet, but I don’t see how they can speed fat loss. Keto OS claims you can eat higher carbs and still see the benefits of ketosis. I don’t see how that is possible. the whole point of weight loss through ketosis is the breaking down of your own fat to create energy. I don’t see how exogenous energy will increase natural fat breakdown. I wish I could get a straight answer to this from somebody.
Is keto safe? Putting yourself through this type of therapy isn't always easy and the process can take some getting used to, in particular during the initial stages when people must go through a period of fasting in order to raise ketone bodies faster. Of course, by doing this, it can put your body through a bit of shock and may cause a person to experience some short-term side effects until their bodies begin to adapt to the lifestyle and any BHB supplement they may be taking.
MCT oil is extracted primarily from coconut oil, and derives unique benefits from its shorter fatty acid chain length. Most dietary fat contains 12 carbons in the fatty acid chain, while MCTs are only 6 - 12 carbon chains in length. Shorter chain length allows for easier absorption and rapid conversion to energy in the liver, specifically caprylic (C8) and capric (C10).
Athletic performance benefits: The use of exogenous ketone supplements for bettering physical/athletic performance is promising for several reasons. Firstly, taking exogenous ketones (particularly BHB salts) induces acute nutritional ketosis for upwards of eight hours, mimicking fasting physiology (e.g. increases fat burning, insulin sensitivity, etc.).[3]
Exercising is undoubtedly important when it comes to losing weight. An added bonus of being in a state of ketosis is the ability to improve your exercise performance, but you should also remember that entering ketosis for the first time can be a bit of a challenge for a lot of people. The body is still adjusting to such a dramatic diet change, so exercising may prove to be difficult at first. The key here is to keep going.
To enter ketosis, up to 80%of your daily calories should come from fat. To put this into a frame of reference, if you eat 2,000 calories a day, 1,600 of those calories should come from fat sources. This comes out to roughly 144-170 grams of fat. Both quantity and quality are equally important, so consume fats from high-quality sources, like omega-3 and omega-6 fatty acids.
Various reasons can motivate you to get into ketosis as part of the Ketogenic Diet. These may range from medical purposes so that you stay healthy, to keeping various ailments away. If you are an athlete, you may get into ketosis to keep your body fit for the upcoming competitions. Some people get into ketosis just to shed some extra fat and keep their bodies in perfect shape. Regardless of the reasons, here are practical tips on how to get into ketosis in 24 hours.

Recent studies suggest that many of the benefits of the KD are due to the effects of ketone body metabolism. Interestingly, in studies on T2D patients, improved glycemic control, improved lipid markers, and retraction of insulin and other medications occurred before weight loss became significant. Both βHB and AcAc have been shown to decrease mitochondrial reactive oxygen species (ROS) production [36–39]. Veech et al. have summarized the potential therapeutic uses for ketone bodies [28, 40]. They have demonstrated that exogenous ketones favorably alter mitochondrial bioenergetics to reduce the mitochondrial NAD couple, oxidize the co-enzyme Q, and increase the ΔG’ (free enthalpy) of ATP hydrolysis [41]. Ketone bodies have been shown to increase the hydraulic efficiency of the heart by 28 %, simultaneously decreasing oxygen consumption while increasing ATP production [42]. Thus, elevated ketone bodies increase metabolic efficiency and as a consequence, reduce superoxide production and increase reduced glutathione [28]. Sullivan et al. demonstrated that mice fed a KD for 10–12 days showed increased hippocampal uncoupling proteins, indicative of decreased mitochondrial-produced ROS [43]. Bough et al. showed an increase of mitochondrial biogenesis in rats maintained on a KD for 4–6 weeks [44, 45]. Recently, Shimazu et al. reported that βHB is an exogenous and specific inhibitor of class I histone deacetylases (HDACs), which confers protection against oxidative stress [38]. Ketone bodies have also been shown to suppress inflammation by decreasing the inflammatory markers TNF-a, IL-6, IL-8, MCP-1, E-selectin, I-CAM, and PAI-1 [8, 46, 47]. Therefore, it is thought that ketone bodies themselves confer many of the benefits associated with the KD.
Studies show that exercising depletes both liver and muscle glycogen faster than fasting [4]. For example, swimming for an hour and a half depletes the same amount of glycogen as a 24-hour fast. However, it's a good idea to eat a tiny amount of carbs and protein before and after a workout to prevent muscle damage. Your body can break down proteins in your muscles if glycogen stores get depleted during workouts.

One other thing I must point out is also that we are talking about being in ketosis and not being fully keto adapted. You enter ketosis when your body starts producing ketones above a specified level, being fully keto adapted means that your body is full adapted to  use fat as your primary energy source and that the production of certain enzymes in your body is fully adapted. This doesn’t happen in one day and it takes about 1 month on average to be fully keto adapted. But we are not looking for this as we just want to end the most unpleasant period and to start losing weight.

Why is this desirable? Think about energy production in your body much like macro energy consumption on a planetary level. Coal is gross and dirty and messes tons of different things up. You need to continue to burn it to get energy. Solar power is free, clean and pretty much limitless. This is pretty much the same story when you are burning carbs (coal) versus fats (solar) for energy.

Once the body is able to generate energy with the help of exogenous ketones which are present in the bloodstream, it would start looking for other sources of ketones. This would encourage the body to tap into the vast reserve of fat which is accumulated in the body. Thus, the process of ketosis is accelerated when you consume extra exogenous ketones. This also leads to quicker weight loss and the body entering ketosis faster.

If you read about ketosis in magazine or heard about it in a podcast and wanted to jump on the bandwagon, then I think you should avoid it. Remember, it is a strict diet, and the potential health downsides may not be worth the upsides, unless you are working with a medical professional and or you are tracking your labs to see what’s going on with your health (thyroid).
Exogenous ketones cause the body to rely less on fat as fuel (see Fig 3). Fat takes longer to metabolise for energy than muscle glycogen. This is why fatty acids are not the preferred fuel under heavy exercise. This could be useful for keto-adapted athletes performing high-intensity cardiovascular or strength training.12 This is particularly useful for the Keto-adapted athlete who wants to undergo high-intensity cardiovascular or strength training.
Over the 28-day experiment, ketone supplements administered daily significantly elevated blood ketone levels without dietary restriction (Fig. 2a, b). Naturally derived ketogenic supplements including MCT (5 g/kg) elicited a significant rapid elevation in blood βHB within 30–60 min that was sustained for 8 h. BMS + MCT (5 g/kg) elicited a significant elevation in blood βHB at 4 h, which was no longer significant at 8 h. BMS (5 g/kg) did not elicit a significant elevation in blood βHB at any time point. For days 14–28, BMS + MCT (10 g/kg) and MCT (10 g/kg) elevated blood βHB levels within 30 min and remained significantly elevated for up to 12 h. We observed a delay in the peak elevation of blood βHB: BMS + MCT peaked at 8 h instead of at 4 h and MCT at 4 h instead of at 1 h. Blood βHB levels in the BMS group did not show significant elevation at any time point, even after dose escalation (Fig. 2a). Synthetically derived ketogenic supplements including KE and BD supplementation rapidly elevated blood βHB within 30 min and was sustained for 8 h. For the rats receiving ketone supplementation in the form of BD or the KE, dosage was kept at 5 g/kg to prevent adverse effects associated with hyperketonemia. The Precision Xtra™ ketone monitoring system measures βHB only; therefore, total blood ketone levels (βHB + AcAc) would be higher than measured. For each of these groups, the blood βHB profile remained consistent following daily ketone supplementation administration over the 4-week duration. (Fig. 2b).
Fortunately a new way to test ketosis has been developed - and that is by measuring acetone levels in the breath. This is rather new technology but based on the reports I have seen it does look reasonably reliable. The testing process is simple, you use a device like that made by Ketonix, you breathe into it, wait a minute or so and it will give you a color indicating the state of ketosis you are in. However, there are numerous downsides:

If you have already mastered the Very Low Carbohydrate (VLC) or ketogenic way of eating, and/or are eating at a caloric deficit, exercising or fasting you are naturally creating the optimal conditions for your body to produce ketones and put your body into nutritional ketosis. By strict adherence to a well-formulated ketogenic diet (complete with higher levels of mineral salts) you should be able to produce all the ketones you need naturally (endogenously). If you are new or inexperienced in ketogenic eating however; or if you or a family member struggles to adhere to a ketogenic diet, then supplementation with exogenous ketones may be very beneficial. Not only will ketone supplements help to mitigate hunger and carb cravings, but they will also help you stave off carb flu symptoms (see below), giving you the best possible chance of long-term success.
The ketogenic journey should be more of a lifestyle than one that acts like a fad. So taking more than a day for your body to enter ketosis should not be the greatest of concern. It’s more important to stay discipline and to consistently keep your body in a fat-burning state. Although, if you are someone who has fallen out of ketosis after a cheat day, or rather somebody who is just starting out and finding it longer than expected to enter ketosis, then this article can definitely help in that respect. It’s nothing new, and it’s definitely no secret but strict dieting, fasting, exercise, controlling stress levels, sleep, and certain supplements can help you boost ketogenesis!
Hi! I have what might be a silly question about using these supplements. What happens if you are taking them and your diet goes off the rails, like you take the Keto//OS and then eat a bunch of pizza or chocolate. Does your body just immediately revert back to using the carbs for energy instead of the ketones? Or, if it doesn’t, would that mean your body would just store those carbs as fat? I realize that ideally you wouldn’t eat the pizza, but sometimes I do and I worry about what exactly I’m doing to my body if I’ve also taken ketones.
Ketones may be a better source of fuel than glucose, and a far better beverage than Fruitopia, but it's a question of whether or not you can spare the extra fuel. Because just like adding sugar to a diet, it's like pressing pause on the fat burning process since the body preferentially burns it for fuel. Adding ketones to the diet does the same thing.
Proponents like Heverly say that taking exogenous ketones can transform your body—and your life. (Her before-and-after shots below were taken just 10 days apart.) “Within 10 days, my body had this shift. My midsection wasn’t as bloated or fluffy. And I don’t have that cellulite on my legs now,” she says. Heverly also credits Prüvit with giving her a much-needed energy boost and improved mental clarity.
SHEER Ketones BHB Salts made this top 5 list because they do a good job of avoiding all the common unwanted additives and fillers in BHB salts. It’s good to see we have options to choose from when trying to avoid these types of ingredients. SHEER Ketones’ other ingredients include citric acid, fruit and vegetable juice powder for the color, and “natural flavors.” It uses a stevia leaf extract (Rebaudioside A).
2. Shimazu, T., Hirschey, M.D., Newman, J., He, W., Shirakawa, K., Le Moan, N., Grueter, C.A., Lim, H., Saunders, L.R., Stevens, R.D., Newgard, C.B., Farese Jr, R.V., De Cabo, R., Ulrich, S., Akassoglou, K., and Verdin, E. (2013). Suppression of oxidative stress by β-hydroxybutyrate, an endogenous histone deacetylase inhibitor. Science 339, 211-214.

The way you make an exogenous BHB is by attaching it to some type of other compound (sodium, potassium, calcium, or magnesium) so that your body can process the molecule by cleaving the bond between the salt and the beta hydroxybutyrate. BHB + bound to a salt = BHB salts, which is what most people in the ketosis community call exogenous ketones. There are also things called esters, which are basically unbound BHB molecules. These are really disgusting and cause massive digestive issues, so I like to ignore them until we can produce them in a more appealing way.

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