For the past few million years, the only way for humans to make use of ketones for fuel was to restrict carbohydrates low enough and long enough to induce the liver to make them. This is admittedly hard for many people to do in a world that still believes that dietary carbs are good and fats are bad. An emerging alternative is to consume ketones as a dietary supplement. The research into how these function in the body and what benefits they can confer remains early stage, but there are already a number of such products available for sale. In this section, we will discuss how exogenous ketones affect blood ketone levels, and how they may influence health and disease compared to ketones produced within the body.
Ketone Salts: While the body uses and makes BHB ketones salts naturally, in supplement form ketone salts are synthetically (lab) made compounds that combine sodium (and/or potassium, calcium, or magnesium) with BHB. The salt is used to raise the pH and make things less acidic. Currently, all ketone supplements on the market are made from ketone salts. While they raise ketone levels, most people will only experience mild nutritional ketosis (~0.6-1.0 mmol/L).
Another important difference between endogenous and exogenous BOHB is that most synthetic BOHB used in dietary supplements is a mixture of the two ‘D’ and ‘L’ isomers, whereas endogenously produced BOHB consists of just the D-isomer. Metabolically, the two isomers are very different, and current published information indicates that most of the energy and signaling benefits of BOHB derive from the D-form. This is potentially problematic because the L-isomers are not metabolized via the same chemical pathways as the D-forms (Lincoln 1987, Stubbs 2017), and it remains unclear whether humans can convert the L-form to the D-form.

Exogenous ketones don’t seem to improve high-intensity, glucose-intensive exercise, increasing fat burning during steady state exercise but dropping top-end high-intensity performance. Another study found that ketone dieters reduced 50-minute time trial performance in cyclists, though another group of researchers have criticized the methods. Even when a ketone ester didn’t improve performance in the shuttle run to exhaustion and 15 meter sprint repeats, it did reduce the drop in brain function following the exercise.

Comments are welcomed and encouraged. The purpose of comments on our site is to expand knowledge, engage in thoughtful discussion, and learn more from readers. Criticism and skepticism can be far more useful than praise and unflinching belief. There’s an art and science to critical thinking and how to conduct yourself. There’s a multitude of fallacious appeals we could spell out, but a good rule of thumb is not to attack the person, attack the ideas. Don’t look for the flaws in the person, look for the flaws in the hypothesis. Let’s keep the brawling to movies depicting minor league hockey teams and political “news” shows. Thank you for adding to the discussion.
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).

Although several studies have linked calcium supplementation with an increased risk of heart attack and heart disease[18], other studies have not found the same association. For example, a study on calcium supplementation (1000 mg/day) in postmenopausal women indicated a reduced risk of hip fracture, but no increase in cardiovascular disease or mortality in the supplement group, compared to the placebo group[19]. Another study found no effect from calcium supplementation (600 or 1200 mg/day) on abdominal aortic calcification[20].
Ketones are naturally slightly acidic, so the combination of BHB with sodium acts as a bit of a buffer to this acidity. Ketones will also naturally act as a diuretic, so you lose salt, potassium calcium and magnesium, and it is generally encouraged to increase sodium intake with ketones. The addition of sodium to the product will replenish this salt loss.
Skipping breakfast on a keto diet is a popular way to boost ketone levels. Despite the age-old myth that breakfast is the most important meal of the day, research shows that breakfast skipping is not only safe but beneficial. Skipping breakfast causes intermittent ketosis and also suppresses appetite [6]. Make sure your next meal of the day isn't too late in the evening as studies show that eating meals late at night causes weight gain and impairs fat metabolism [7].
Possible GI distress (flatulence) at exceptionally high doses –  In the studies referenced in this article, exogenous ketones taken in large doses occasionally resulted in GI distress, especially flatulence. However, the cause of this is hypothesized to be due to the fact that ketones were mixed in a milky fluid that wasn’t very palatable. If you’re taking a nominal dose of exogenous ketones the likelihood of GI distress is rather low. Moreover, if some GI distress is prevalent, it should improve as you become accustomed to taking ketones.
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.
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).
If the color is close to the original beige of the test strip, it means there are few if any ketones in your urine and you’ll need to make some dietary tweaks. This may include eating less fat. That’s because if you have doubled down on the healthy fats your body may be rebelling. One way to tell is if you are constipated. If you think this is the case, ratchet back the fats by 50% and see if it makes a difference. 
While exogenous ketones (EK) are a newer supplement, having entered the market for consumers in just the past few years, scientists have been synthesizing ketone bodies in a lab since the 1960’s. They were useful for scientists studying their use for specific disease conditions, most notably childhood seizure disorders, though they were prohibitively expensive for consumers (1, 2).
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]
One thing to remember here is that even if your calculated daily ‘keto approved’ protein allowance is (let’s say) 150g, that doesn’t mean you can eat 150g in one meal and still be in ketosis. You may find that you can’t eat more than 40g of protein at a time, otherwise you will drop out of ketosis. OR, you may find you can eat 50g of protein but you need a LOT of fat. Whereas a small serve of 15g of protein without fat might knock you out of ketosis. 
Increased calcium levels in the bloodstream may contribute to the hardening of arteries (atherosclerosis), which in turn can lead to a heart attack.  Calcium from supplements enters the bloodstream in one bolus, whereas we usually tend to get calcium from foods in small doses from the breakdown process. This might explain why calcium from food doesn’t create the same risk that is introduced by calcium supplements. At first glance, it seems to be the case that high calcium intake –at least from supplements–may not be ideal.
Onnit is an incredible company that’s making a massive impacts in the lives of athletes in nearly every sport. From Olympic Gold Medalists, to NFL middle linebackers, Onnit has taken athletic performance to a new level. Providing supplements, food, and training equipment, Onnit was an early adopter of the elite performance booster that is exogenous ketones!
The product does not work. I have taken one scoop daily and for last two days two scoops (once in the morning and once in the night). I also do intermittent fast i.e. no food from 8 pm - next day 2 pm other than this powder in the morning. My food is 1500 calories with 60% fat, 30% protein and 5% carbs. I used to achieve ketosis naturally prior to using the powder. But now, there is no ketosis. This product does not work. I am wondering how on earth did they pick up so many reviews, unless it is faked marketing.
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.

I eat one meal a day during a one-hour window and fast 23 or more hours every day. I want to use your ketones to get back into ketosis faster after that meal. Will that work? I am confused, because say at the end of my hour eating window I drink your ketones, sure there are lots of ketones suddenly in my body but I also have a big meal in my stomach. My body has to digest and use that food energy, so how do exogenous ketones help me in that case?

There is so much talk about the benefits of a ketogenic diet and its ability to improve fat burning, brain health, energy and anti-aging.  The main units of energy on a ketogenic diet are ketone bodies, of which beta hydroxybutyrate (BHB) is the main player!  This article will go over the health benefits of BHB and exogenous ketones. Additionally, this article will cover strategies on using exogenous ketones in your daily life.
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.
However, it's important to NEVER overlook the power of exercise and of course sticking to a proper routine to get the most optimized results. The most common mistake people make is by treating any keto supplement like a "wonder drug" that will help them shed weight in their sleep. Seriously... how is that even scientifically possible. So if you are thinking about trying out a particular keto supplement, I would suggest two things:

Administration of ketone supplementation significantly reduced blood glucose over the course of the study (Fig. 3a, b). MCT (5 g/kg) decreased blood glucose compared to control within 30 min which was sustained for 8 h at baseline and at week 1. MCT (10 g/kg) likewise decreased blood glucose within 30 min and lasted through the 12 h time point during weeks 2, 3, and 4. BMS + MCT (5 g/kg) lowered blood glucose compared to control from hours 1–8 only at week 1. BMS + MCT (10 g/kg) lowered blood glucose compared to control within 30 min and remained low through the 12 h time point at weeks 2, 3, and 4. Rats supplemented with BMS had lower blood glucose compared to control at 12 h in week 4 (10) (Fig. 3a). Administration of BD did not significantly change blood glucose levels at any time point during the 4-week study. KE (5 g/kg) significantly lowered blood glucose levels at 30 min for week 1, 2, 3, and 4 and was sustained through 1 h at weeks 2–4 and sustained to 4 h at week 3. (Fig. 3b).
Animal research findings report that BHB supplementation also enhances oxygen utilization, especially in the central nervous system (CNS).[11] While molecular oxygen is a crucial molecule for health and longevity, too much of it can be potentially toxic and speed the effects of aging in tissues throughout the body.Therefore, using a BHB supplement can effectively mitigate the toxic buildup of molecular oxygen, particularly in the CNS/brain.
If you have been reading the science behind the ketogenic diet, you know there can be a lot of benefits associated with choosing this way of eating. There is usually a transition period from when someone chooses to go on a ketogenic diet and implements the changes to their menu to when they actually get into ketosis and are able to produce and burn ketones for fuel.

I also chatted to some Prüvit reps, who told me that it might be necessary to keep taking the supplements for a couple of months to start to see more elevated ketones. Well, the proof is in the pudding (or in this case, in the fluorescent-coloured, artificial-tasting pink drink). But I would hesitate before spending money on a two-month supply just to find out if that’s true. Real Ketones’ Kegenix Prime was associated with a decrease blood ketones. Not a good start, and we’ll get back to this point later.
When taken as a drink, the ester bonds are broken down to release butanediol (BDO) and D-BHB into the blood. BDO is easily metabolized by the liver to form D-BHB. Then, both molecules of D-BHB reach the blood, as the liver is unable to use ketones. Consumption of this ketone ester elevates blood ketone levels in humans safely, with few side effects.10 HVMN Ketone is WADA compliant and safe to use in all levels of sports. It is designated as a foodstuff and is FDA GRAS. Each lot is 3rd party certified and batch tested for banned substances. 

Caveat emptor: the following post doesn’t come close to answering most of these questions. I only document my experience with BHB salts (and a non-commercial version at that), but say little to nothing about my experience with BHB esters or AcAc esters. But it will provide you will some context and understanding about what exogenous ketones are, and what they might do for athletic performance. We’ll likely podcast about the questions and topics above and cover other aspects of exogenous ketones in more detail.

Affiliate Disclosure: There are links on this site that can be defined as affiliate links. This means that I may receive a small commission (at no cost to you) if you purchase something when clicking on the links that take you through to a different website. By clicking on the links, you are in no way obligated to buy.

Medical Disclaimer: The material on this site is provided for informational purposes only and is not medical advice. Always consult your physician before beginning any diet or exercise program.

Copyright ©