MCT oil has recently been used to induce nutritional ketosis although it produces dose-dependent gastrointestinal (GI) side effects in humans that limit the potential for its use to significantly elevate ketones (>0.5 mM). Despite these limitations, Azzam and colleagues published a case report in which a 43-year-old-man had a significant decrease in seizure frequency after supplementing his diet with 4 tablespoons of MCT oil twice daily [96]. An attempt to increase his dosage to 5 tablespoons twice daily was halted by severe GI intolerance. Henderson et al. observed that 20 % of patients reported GI side effects with a 20 g dose of ketogenic agent AC-1202 in a double blind trial in mild to moderate Alzheimer’s patients [24]. We visually observed similar gastrointestinal side effects (loose stools) in the rats treated with MCT oil in our study. Rats were closely monitored to avoid dehydration, and gastric motility returned to normal between 12–24 h. Interestingly, the BMS + MCT supplement elevated βHB similarly to MCT oil alone, without causing the adverse gastrointestinal effects seen in MCT-supplemented rats. However, this could be due to the fact in a 10 g/kg dose of BMS + MCT, only 5 g/kg is MCT alone, which is less than the 10 g/kg dose that elicits the GI side effects. This suggests that this novel combination may provide a more useful therapeutic option than MCT oil alone, which is limited in its ability to elevate ketones in humans.
The two compounds commonly referred to as ‘ketone bodies’ (BOHB and AcAc) are produced and used for multiple purposes across nature from algae to mammals, but seldom in concentrations useful for extraction as human food. For this reason, the source of most exogenous ketones is chemical synthesis. Furthermore, most current research and use of ketone supplements focuses on BOHB. That is because AcAc is chemically unstable – it slowly breaks down to form acetone by releasing of one molecule of CO2.
Let’s briefly discuss some organic chemistry. Two molecules that are “the same” but mirror images of each other (like your hands) are known as enantiomers, a type of spatial isomer. Beta hydroxybutyrate comes in two forms, D-β-hydroxybutyrate (“right-handed”) and L-β-hydroxybutyrate (“left-handed”). D-β-hydroxybutyrate is the form that is naturally produced in the body and is most bioavailable when taken exogenously.
Usually, you’ll find exogenous ketones in the form of powdered ketone salts. Less common are ketone esters, which are the purest form of ketones. Griffin says they work quickly (in 10 to 15 minutes, as opposed to an hour for the salts) and effectively, but they’re more expensive, have a more-revolting taste, and are harder to find (HVMN is one U.S. company that sells them). People also use medium-chain triglyceride (MCT) oil — or partially manmade fats — to put the body into a state of ketosis.
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.
The CNS cannot use fat as an energy source; hence, it normally utilizes glucose. After 3–4 days without carbohydrate consumption the CNS is ‘forced' to find alternative energy sources, and as demonstrated by the classic experiments of Cahill and colleagues4 this alternative energy source is derived from the overproduction of acetyl coenzyme A (CoA). This condition seen in prolonged fasting, type 1 diabetes and high-fat/low-carbohydrate diets leads to the production of higher-than-normal levels of so-called ketone bodies (KBs), that is, acetoacetate, β-hydroxybutyric acid and acetone—a process called ketogenesis and which occurs principally in the mitochondrial matrix in the liver.6

This process can be used as a way to get you into ketosis more quickly, so you can transition gracefully into a ketogenic lifestyle or as a way to stimulate autophagy and fat loss. If you can’t go without fat for the full 3 day fast — it’s okay — you will still illicit many of the benefits of fasting by limiting your protein and carbohydrate intake.
The concentrations of blood d-βHB after KE drinks were highly repeatable whether consumed whilst fasted or fed (Figures 4F,G). The d-βHB Cmax values ranged from 1.3 to 3.5 mM when fed and 2.3 to 4.7 mM when fasted. There was no significant effect of visit order on d-βHB kinetics, with the maximal difference in d-βHB Cmax reached by one individual being 1.2 mM when fed and 1.9 mM when fasted. Approximately 61% of the variation in the data was attributable to feeding (fed vs. fasted), <1% to visit order, 16% to inter-participant variability, and the residual 24% variability due to non-specific random effects.
Im very excited about this product! I received it about a week ago and it helped me break my month+ plateau! I've been on a keto diet since mid-April and had lost 10 lbs but stalled out. Ill be honest, the after taste is not pleasant but I'll take it since it's working. I've lost 12.5 lbs and going strong. Feeling better than ever. Would recommend and buy again!
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.
Also, this experiement should be of interest. Two men followed a ‘traditional Eskimo’ diet for 1 year. After the year eating a low carb high fat diet, it was found that the men had a diminished tolerance to carbohydrates, something that did not occur in Eskimos eating the same diet. It took the mean nearly a month of eating a ‘normal diet’ before their glucose tolerance returned to baseline. 

As stated above, there appears to be a difference between supplemental and dietary calcium intake, which can be important to keep in mind.  One study found aggregate calcium intakes above 1400 mg per day (from dietary and supplemental intake combined) to be associated with higher death rates, cardiovascular disease, and ischemic heart disease in women[15]. A 2014 meta-analysis found an association between dietary calcium intake and cardiovascular mortality[16]. The meta-analysis actually found a u-shaped relationship, where dietary calcium intakes that were both lower and greater than 800 mg/day were gradually associated with increased risk of cardiovascular mortality.

While we know that both MCT Oil Powders and BHB salts are proven supplements to increases ketosis, the winner of a top 5 exogenous ketones list I think should be a true direct form of exogenous ketones – one of the BHB salts. Perfect Keto’s BASE takes the win here. The edge ranking factor is its flavor. With stevia-based flavors such as chocolate sea salt, and the fact that it uses zero additives and actually tastes good, this BHB salt is going to have to take the W. They’re the only 100% coconut MCTs that don’t utilize the goMCT™ form.. this is neither a pro or con. And while it doesn’t have the best bang for your buck compared to the other BHB salts on this list, it’s the most proven as far as happy customer track record and consistent high-quality keto supplements.
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!
In fact this was one of the biggest surprises I had when exploring ketosis. For years I have been following a cyclical lower carb diet. For years I wouldn’t consume a carb until later in the afternoon (ala Carb Backloading style). After eating 5 days without any carbs I tested my ketone levels… they were 0.1 mmol. This reading was done first thing in the morning (10 hours fasted) after 5 days without a carb in my diet.

You may find a tiny amount here and there is ok (i.e., 2g of sugar with a meal full of fat may be ok).  But if you are starting out I would recommend cutting all sugar from your diet, and most importantly avoiding any sugar consumption on an empty stomach. For best results track your ketone levels before and after meals to see the impact the food has on your ketone levels.
And zero-carb, followed by fasting for two meals, and then followed up by a second zero-carb meal is almost always all you need to get into ketosis fast. By Sunday or Monday morning, after a second night of no carbs, you’ll be in a deep enough ketosis that hunger will crash and your energy will surge to help you transition into your low-carb diet of choice.
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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.
Yes. Both producing BHB in your liver as well as supplementing with beta hydroxybutyrate very safe. As we mentioned before, levels of 0.5 – 3.0 mmol measured in a blood test are completely normal. Some people get stressed out when they hear the term “diabetic ketoacidosis” or DKA, which is an entirely different metabolic scenario where your BHB levels skyrocket to 15-25 mmol blood readings.

Not only is Ketōnd considered one of the best on ketone supplements the market it also currently holds favorable ratings, reaching numbers as high as 98 percent in customer reviews. They absolutely love this product and you will too if you give it a try. You will get some incredible results. Whether you are a busy professionals, athlete, on-the-go moms or dads, or college students you too will love this product.
Too much cortisol tells the liver that you are in physical danger and need a lot of energy fast. The brain doesn’t understand the difference between physical danger and emotional stress. When emotionally stressed, the brain thinks you’re in a life-and-death situation, so the liver comes to your rescue and gives you the glucose you need to fight off your attacker.

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.

Consuming exogenous ketones isn't the same as following a ketogenic diet–the ketones in the blood haven't been naturally produced by the breakdown of fat stores. However, scientists believe many of the health benefits of the keto diet and fasting (aside from weight loss) are triggered by ketones. Therefore, raising ketone levels through either endogenous or exogenous ketosis could help to improve health and performance by:

It is a good idea to weigh the pros and cons before deciding to add a calcium supplement to your diet. This includes exogenous ketone supplements. If you have any risk factors for osteoporosis, have low bone density, or have issues that prevent you from consuming a nutrient-rich diet, then the benefits of calcium supplements will likely outweigh the risks. But don’t forget that there are other avenues to improving your bone density, like strength training, and, more importantly, a well-balanced diet.
More tolerable than MCT oil: MCT oil has been known to cause gastrointestinal distress in users, especially when taken in higher amounts. Exogenous ketones in the form of ketone salts, in comparison, are well-tolerated. Thus they enable one to avoid adverse GI events while providing the body with similar types of benefits. Figure 2 shows Ketone esters can be effective at reducing appetite. A combination of MCT oil and exogenous ketones may aid weight loss and allow a lower loading of ketone supplements, without the GI distress seen with MCT oil.
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.
Full disclosure: after carrying out the background research, I was already, as you might imagine, feeling a little less neutral about these products. You may have noticed a hint of that in part 1 of the 2-part video series we made about the project (watch part 2 at the top of this page!). However, and although this was by no means a controlled scientific study under laboratory conditions, we designed the experiment in a very objective way. The aim was to give the supplements the best possible chance of showing the benefits they are claimed to have.
So if you really want to jump start ketosis, do what the prehistoric humans did; don’t eat for 3 to 5 days. Keep the water bottle and multivitamins close and go on a strict fast. It might seem extreme and to a degree it is, but starving yourself will put you into ketosis. No ifs, ands, or buts about it. And it will cause you to lapse into a ketogenic state faster than if you tried to do so by manipulating the foods you eat (replacing carbs with fats). Once starvation has caused your body to transition to a ketogenic state, you can begin to introduce your low carb, high fat keto-friendly foods.
I heard a rep from Perfect Keto on a podcast and your Exogenous Ketones. I ordered and received it the other day. I see from this article that I should not do a full scoop at once, but break it up in a day. Good to know. I had about a half scoop before I worked out this morning and could tell I had more energy. Loved that. Just curious….any ideas how long it will take me to get back into ketosis and fat burning?? (I know it depends on what I eat, but a general idea that I promise not to hold you too! (I’m actually missing having ‘keto breath!)
These studies were approved by external Research Ethics Committees (London Queen's Square: 14/LO/0288 and South West Frenchay: 15/SW/0244) and were conducted in accordance with the Declaration of Helsinki (2008). Studies took place at the University of Oxford between September 2014 and September 2016. Participants were healthy, aged 21–57, non-smokers and had no history of major illness. Female participants were using oral contraception to minimize the effects of menstrual phase on results. Participants provided written informed consent prior to inclusion, and completed a confidential medical screening questionnaire to determine eligibility. Anthropometric characteristics are shown in Table ​Table1.1. Sample sizes were chosen following an estimated power calculation based on the effect size in previous work using KE drinks (Clarke et al., 2012b; Shivva et al., 2016).
Intense exercise — more than just fidgeting or pacing — uses ketones, when glucose is in short supply, which means the body has to create more ketones to replace what you use. This is great for those who are used to a moderate to intense activity level, but intensity is a fine dance between encouraging ketone production and elevating cortisol for the rest of us.
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Let’s briefly discuss some organic chemistry. Two molecules that are “the same” but mirror images of each other (like your hands) are known as enantiomers, a type of spatial isomer. Beta hydroxybutyrate comes in two forms, D-β-hydroxybutyrate (“right-handed”) and L-β-hydroxybutyrate (“left-handed”). D-β-hydroxybutyrate is the form that is naturally produced in the body and is most bioavailable when taken exogenously.

When the results for the supplement and the placebo were within 0.2 (either % or mmol/L) of each other, we classed the supplement as neither “better” nor “worse” than the placebo. We gave a “winning brand” sticker to the brand that scored highest against the placebo for each marker, but not for physical performance, since none of the supplements performed better than the placebo for that marker.
All data are presented as the mean ± standard deviation (SD). Data analysis was performed using GraphPad PRISM™ version 6.0a and IBM SPSS Statistics 22.0. Results were considered significant when p < 0.05. Triglyceride and lipoprotein profile data were analyzed using One-Way ANOVA. Blood ketone and blood glucose were compared to control at the applicable time points using a Two-Way ANOVA. Correlation between blood βHB and glucose levels in ketone supplemented rats was compared to controls using ANCOVA analysis. Organ and body weights were analyzed using One-Way ANOVA. Basal blood ketone and blood glucose levels were analyzed using Two-Way ANOVA. All mean comparisons were carried out using Tukey’s multiple comparisons post-hoc test.
Ketone supplements contain exogenous ketones—synthetic ketones made in a lab. Most use a type of ketone called beta-hydroxybutyrate (BHB), which is the same as the ketones the body produces naturally. “We’re literally biohacking," says Amie Heverly, who began taking a ketone supplement called Prüvit last year and now works as a promoter selling Prüvit products. "You’re not adding a foreign substance to your body, because BHB is identical to what your body would naturally produce,” she explains.
Beta hydroxybutyrate floats around in your blood, and importantly, can cross different barriers to be able to be turned into energy at all times. One of the most important areas where this happens is in the brain. The blood-brain barrier (BBB) is usually a very tightly regulated interface that doesn’t allow the transfer of many molecules, but since BHB is such a rock star and so hydrophilic, your brain knows to let it in so it can bring energy to the party at any time. This is one of the main reasons why increased levels of ketosis lead to improved mental clarity, focus and reduction in neurodegenerative diseases.

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.
Hello! I’m planning on taking a short vacation and will be having “kept friendly” drinks, mostly vodka and water with lemon and stevia. When should I take my exogenous ketones? That night before bed or early the next morning or after the 3 day vacation is completely over? I’m unsure how to manage this to have the best odds of staying in ketosis and get back to burning FAT. Also, I just purchased Instaketones from Julian Bakery, what are your thoughts on this brand? Thanks for what you do!
I feel like I should also mention that the GI discomfort is real, people. I would recommend starting this product on a weekend or a day where you’re able to just take it easy. After my first dose, which was only 1/2 scoop, I literally just felt like lying in bed all day due to feelings of nauseousness; however, by the next day I was fine and even bumped my dose to a full scoop.
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.

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