If you’ve done any reading about ketosis, you no doubt read at some point that ketosis is a “natural” state. You may have read on a bit more and learned what is meant by that statement or you may have simply skipped ahead to the keto success stories and decided to give it a try. But we’d like to direct your attention back to that little tidbit of information about keto being “natural” for a moment.

Exogenous ketones (also known as ketone supplements) and well-formulated ketogenic diets share at least one thing in common. They both result in increased circulating concentrations of beta-hydroxybutyrate (BOHB), but ultimately are associated with very different patterns of ketosis, as well as differing metabolic and physiologic outcomes. In short, they should not be assumed to have equivalent effects simply because they achieve similar BOHB blood levels. Having said that, there are many reasons we should continue to study the various forms and potential applications of ketone supplements.
Would this be helpful for someone with Hypothyroidism and HPA Axis dysfunction? I started a Keto/IF lifestyle after watching your videos early July and though I feel so much better inflammation wise, I am not seeming to be super fat adaptive as of yet. Would KetoEdge stress out my body with these things going on? I’d love to try it but want to make sure first.
Compared to our other cellular gasoline (carbs), we can store an unlimited supply of energy from ketones in our body within our fat. When you’re reliant on carbohydrates, you’re forced to keep your tank partly full as we can only store just over 2,000 calories of glycogen from carbs. An empty carb tank results in carb-withdrawal symptoms from not being able to switch into a ketone or fat burning metabolism.
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.
Despite the recent growth of the ketone salt market, there is very little published work analyzing the effects of these products on any biomarkers or performance measurements in humans. Several studies have been carried out in rats,6,7 with blood BHB levels being relatively low (<0.5 mM) post-consumption of salt drinks. In humans, ketone salts provided peak D-BHB levels of 1 mM, whereas the same amount of BHB in a ketone ester (BD-BHB) raised blood BHB to 2.8 mM.5
So I’ve been primarily on a Keto diet for almost 6 months. During this time, I have fine tuned a lot to get my ketone levels up (Eating more fat and less protein). Most recently, I have used blood measurements for my ketone levels and I fluctuate between .6 and 2.6. The higher readings I get on the days I workout in the morning (about 5 hours before I draw blood and take a reading). I don’t have any problems sticking to the diet. It only seems to get easier. I’ve also incorporated 16 hour fasts which also are becoming easier over time. My priority and motivation for doing a keto diet is first and foremost weight loss. So far I have lost 40 pounds and I need to lose about 20 more. I do however want to improve my performance (running) and strength (I am doing the Stronglifts 5×5 program now).

Exogenous ketones can lower appetite during a fast. After an overnight fast, normal weight human subjects either drank a ketone ester supplement or a calorie-matched glucose drink. Compared to the glucose drinkers, the ketone drinkers had lower insulin, lower ghrelin, greater satiety, and less hunger. This can be useful for people trying to extend their fast who don’t want to or can’t yet deal with the hunger. You’re still taking in energy, but the metabolic profile remains similar to that of a fasted person.

77. Volek JS, Sharman MJ, Gomez AL, Scheett TP, Kraemer WJ. An isoenergetic very low carbohydrate diet improves serum HDL cholesterol and triacylglycerol concentrations, the total cholesterol to HDL cholesterol ratio and postprandial pipemic responses compared with a low fat diet in normal weight, normolipidemic women. J Nutr. 2003;133(9):2756–61. [PubMed]
Ketosis is a unique metabolic state where your body burns fat instead of glucose for fuel. Glucose is a simple sugar molecule derived from carbohydrates. Your body prefers using glucose to using fat and protein to make energy. This is because glucose it is easy to burn as it doesn't require much energy. On the other hand, your body uses fat and protein to build and repair tissue and make hormones.
The culprit is often restaurant meals or other meals where the nutrition facts are not available with the food itself. Such “ignorance is bliss” situations allow us to avoid dealing with daunting numbers. Many people don’t hesitate to stop and enjoy a meal at a restaurant, but they freak out when they actually see the numbers on a label.  By now, we all know that opting for fatty meat with a side of veggies cooked in butter isn’t that bad after all.  It turns out that what you thought to be the safe, “healthy,” doctor-approved choice might not always be what you think it is.
Not everything is perfect with Ketōnd, so there are a few things you should know. One is that it is extremely powerful. The company is pretty adamant about taking the correct dosage - and they are right. This isn't your typical ketone supplement. I'd recommend starting off at half a scoop, even if you are used to taking a different ketone supplement. Odds are if you have your product was underdosed. So, it’s kind of a pain to remember all the time, but once you feel good with the half serving then you can work your way up to a full scoop. If you think it is too strong for you – just take one serving a day, not two, and you will be okay.

Even though endurance athletes can train in a carb depleted state, they will generally consume carbohydrates in the lead up to a race (the athlete is seeking to increase the ability to run off fats by training in a carb depleted state, then benefiting from both fats AND carbs come race day). Likewise, with the brain, even though the brain can function off ketones, does it mean it’s the best state for brain function?


I got the Peaches and Cream flavor of Perfect Keto and it's good; a nice sweet break from all the meat, cheese, and vegetables. I would recommend that you use cold water and a shaker bottle though. It takes a bit of vigorous shaking to get the lumps to melt, but it does melt seamlessly. It has a peach taste, but more like a peach with a bitter aftertaste, which I guess is expected with any ketone supplement. I read that a lot of the available supplements taste awful and this one doesn't taste awful. But don't go into it expecting it to taste like a peach pie. :-) I know some of the other supplements say to mix with a keto beverage; I've seen half and half and heavy cream as mixers because the carbs are low and fat high. I haven't tried that as I am only taking in 1,200 calories per day.
There’s debate raging about which dietary tactic is the god particle for making you leaner, faster and healthier. How the ketogenic diet option squares off against the low carb route is vital for understanding the ways in which exogenous ketone supplements work. To get into ketosis the natural way, you need to keep your carb intake low enough for long enough for your body to begin using use fat as fuel. Your liver then converts a portion of that fat into energy molecules called ketones. These work together with glucose as a fuel source, but can actually kick in faster, allowing your body to operate more economically during lengthy, high-energy exercise efforts.
There is a great deal of positive speculation that exogenous ketones can be beneficial for inflammation, cognitive enhancement, and even protection against certain types of cancer. There is mounting evidence that the ketogenic way of eating can help many people, and when used appropriately with realistic expectations, exogenous ketone supplementation can enhance these positive effects (25).

We carried out the testing across five different days, leaving at least two days between the different testing days so that my teammates had time to recover from the physical performance test each time. The reason we needed five days was that we included a placebo (an artificially flavored drink with no caffeine content) alongside the four brands we tested. Our teammates didn’t know that one of the supplements was a placebo. We also gave everyone a different supplement each time, to rule out any improvement in the tests being a result of people simply getting better at those tests over time.
Exogenous ketones supplements is also necessary if you’re wondering how to get into ketosis in 24 hours. Directly ingesting ketones via salts or esters will boost blood ketone levels in the system. These are generally made up of beta-hydroxybutyrate (BHB) which is processed by the body to metabolise into ketones for energy. Some benefits of taking such supplements include anti-inflammatory properties, cancer prevention, increased cognitive function, weight-loss, and athletic performance enhancement.
Exogenous ketones are also for those just looking to try it out. It lets anyone be able to access ketones simply by consuming these exogenous forms of ketones. Technically, MCTs are not an exogenous ketone such as BHB salts. They’re not ketones. But they readily convert into ketones. So MCT oils and powders are a great source of endogenous ketones. The end result is similar, and thus this top 5 list includes MCT oil powders as well as BHB salts.
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.

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.


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.
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. 
I had heard horror stories about how bad ketone esters tasted (like “rocket fuel”!) so was prepared for the worst. I followed their instructions and drank the contents of the bottle in one gulp, then chased it with a sip of sparkling mineral water. While not the most pleasant aftertaste, the flavor wasn’t any worse than after a shot of well tequila. Within 15 minutes I was already well into therapeutic ketosis, and after 30 minutes my ketone meter displayed a “HI” error message (meaning my level was greater than 8.0 mmol/L)!
The other potentially important distinction between nutritional ketosis and chemically-induced ketosis is the potential metabolic role played by liver AcAc production and redox status. Although the ratio of BOHB to AcAc in venous blood is typically 80% to 20%, classic studies by Cahill (1975) have observed important hepatic vein and peripheral arterio-venous gradients for this ratio in keto-adapted patients. What these observations imply is that the liver produces a higher proportion of AcAc than is found in the peripheral blood, and that this is due to uptake of AcAc in peripheral cells (principally muscle) with re-release as BOHB. In the process, the reduction of AcAc to BOHB produces NAD+, which is beneficial to mitochondrial redox state and mitochondrial function (Verdin 2015, Newman 2017).
It's important to listen to your body when going through the ketogenic process. This means that you should only eat when you're hungry and not every single time you get a craving. It's our obsession with food that causes us to stuff ourselves whenever we feel like it, and you should know by now that it's not healthy to do that. When you make it a point to eat only when you're hungry, you're diminishing any food intake that your body doesn't really need. 
One common concern regarding the KD is its purported potential to increase the risk of atherosclerosis by elevating blood cholesterol and triglyceride levels [55, 56]. This topic remains controversial as some, but not all, studies have demonstrated that the KD elevates blood levels of cholesterol and triglycerides [57–62]. Kwitervich and colleagues demonstrated an increase in low-density lipoprotein (LDL) and a decrease in high-density lipoprotein (HDL) in epileptic children fed the classical KD for two years [27]. In this study, total cholesterol increased by ~130 %, and stabilized at the elevated level over the 2-year period. A similar study demonstrated that the lipid profile returned to baseline in children who remained on the KD for six years [63]. Children typically remain on the diet for approximately two years then return to a diet of common fat and carbohydrate ingestion [64]. The implications of these findings are unclear, since the influence of cholesterol on cardiovascular health is controversial and macronutrient sources of the diet vary per study. In contrast to these studies, the majority of recent studies have suggested that the KD can actually lead to significant benefits in biomarkers of metabolic health, including blood lipid profiles [65–72]. In these studies, the KD positively altered blood lipids, decreasing total triglycerides and cholesterol while increasing the ratio of HDL to LDL [68–77]. Although, the KD is well-established in children, it has only recently been utilized as a strategy to control seizures in adults. In 2014, Schoeler and colleagues reported on the feasibility of the KD for adults, concluding that 39 % of individuals achieved > 50 % reduction in seizure frequency, similar to the results reported in pediatric studies. Patients experienced similar gastrointestinal adverse advents that have been previously described in pediatric patients, but they did not lead to discontinuation of the diet in any patient [78].
The difference in peak blood d-βHB concentrations between matched amounts of βHB as ester or salts arose because the salt contained l-βHB, as the blood concentrations of d- plus l-βHB isoforms were similar for both compounds. It is unclear if kinetic parameters of KE and KS drinks would be similar if matched d-βHB were taken in the drinks. Unlike d-βHB, blood l-βHB remained elevated for at least 8 h following the drink, suggesting an overall lower rate of metabolism of l-βHB as urinary elimination of l-βHB was in proportion to plasma concentration. Despite similar concentrations of total βHB, breath acetone was ~50% lower following KS drinks compared to KE, suggesting fundamental differences in the metabolic fates of D- and L-βHB. These findings support both previous hypotheses (Veech and King, 2016) and experimental work in rats (Webber and Edmond, 1977), which suggested that the l-isoform was less readily oxidized than the d-isoform, and is processed via different pathways, perhaps in different cellular compartments. It seems that l-βHB is not a major oxidative fuel at rest, and may accumulate with repeated KS drinks. However, the putative signaling role of l-βHB in humans remains unclear. In rodent cardiomyocytes, l-βHB acts as a signal that modulates the metabolism of d-βHB and glucose, Tsai et al. (2006) although no differences in blood glucose were seen here. Furthermore, L-βHB can act as a cellular antioxidant, although to a lesser extent than D-βHB (Haces et al., 2008).

The effects of ketone drinks on endogenous insulin secretion are unclear. Whilst the small increase in plasma insulin after KE and KS drinks may have been due to the small quantity of dextrose in the diluent, it has been proposed that ketones could potentiate or even stimulate insulin secretion. Isolated pancreatic islets secreted insulin when stimulated by ketones at glucose concentrations of >5 mM (Biden and Taylor, 1983), and small amounts of insulin are secreted in vivo following exposure to exogenous ketones in animals (Madison et al., 1964; Miles et al., 1981). In response to an intra-venous 10 mM glucose clamp, ketone ester drinks increased glucose uptake and plasma insulin (Holdsworth et al., 2017). The increases in insulin with ketone drinks taken whilst fasted were small compared to the increases seen when the ketone ester drink was consumed with a meal and with consumption of a dextrose drink. Furthermore, the lack of difference in peak plasma insulin between the two latter conditions indicates that nutritional ketosis did not inhibit or increase normal carbohydrate induced insulin production.
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.
No additives: Perfect Keto BASE is a bhb supplement keto drink that provides keto salts, contains ZERO carbs, ZERO gums or fillers, and ZERO sugars. Check the labels of other exogenous ketone products and you'll find plenty of gums, binders, fillers and other junk. Not here. Nothing but pure, effective exogenous ketones supplement designed to optimize your ketogenic state
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.
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.
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.
We sampled each of the 3 flavors and also mixed in the available Ketōstax and this supplement tasted better than any other we had tried. Ketōnd costs $79.95 for 30 servings which is about $2.67 per serving – which is less than half the price of the leading competitor. Ketōnd’s label and ingredients are 100% transparent, so they disclose everything that is in the supplement – which is only ketones. What we really liked about Ketōnd is that it isn’t part of some Multi Level Marketing company so there are no obligations.
 “Though the small amount of carbohydrates in the diets may be more than balanced by the potential sugar production from the large amount of protein to keep the ratio of fatty acid to glucose below the generally accepted level of ketogenesis, the respiratory quotient data suggest another mechanism also” ß (most likely the CPT-1A mutation, which had not been discovered at that time)

Of course, there may be some people who choose to take these supplements because they genuinely do feel they benefit from them. This is of course your choice and this article in no way aims to shame or criticize anybody. However, I do think that, for most people, eating a low-carb diet based on real foods is a lot more likely to be associated with the benefits that the supplements claim to provide than the supplements themselves.


Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...
Beta-hydroxybutyrate (BHB) is a ketone body produced in the liver naturally under conditions when glucose isn’t very available. Other types of ketones produced via the restriction of dietary carbohydrates are acetoacetate and acetone. A VLCHF or ketogenic diet provides the optimal conditions for this process. Fasting, exercise and/or basic caloric restriction are all also methods for promoting ketogenesis (literally, the making of ketones).
Ketogenic Diets and Physical Performance – Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis. (http://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-1-2)
Beta-hydroxybutyrate (BHB): Nutrition strategies that rely on carbohydrates always leave us needing more food. On the other hand, the ketogenic diet relies on and taps into your body’s stored fat for longer, more stable energy with no bonking. Many keto-lovers adopt this lifestyle because they love the mental clarity, focus, and productivity that they experience while in ketosis. Whether you’re full-time keto or not, our Perfect Keto is designed to support ultimate mental performance.
Blood glucose concentrations are decreased during both exogenous and endogenous ketosis, although by different mechanisms. During endogenous ketosis, dietary carbohydrate deficit is the underlying cause of low blood glucose, along with reduced hepatic gluconeogenesis and increased ketone production (Cahill et al., 1966). With exogenous ketosis, carbohydrate stores are plentiful, yet ketones appear to lower blood glucose through limiting hepatic gluconeogenesis and increasing peripheral glucose uptake (Mikkelsen et al., 2015). One clinical use of the ketogenic diet is to improve blood glucose control, yet the elevated blood FFA may increase the risk of heart failure (Holloway et al., 2009). Thus, the ability of exogenous ketones to lower blood glucose without elevating blood FFA concentrations could deliver the desired effect of the diet, whilst also decreasing a potential risk.
Great question. We can’t see any reason this can’t be a part of a successful weight loss program on the ketogenic diet. In the morning with coffee is a very popular way to raise ketone levels in the morning. See if you are on pace with your goals and perhaps try a week with a different breakfast to see what feels best. Also – new article might be helpful here too: https://perfectketo.com/exogenous-ketones-for-weight-loss/ Good luck! 🙂
If you’re wondering how to get into ketosis in 24 hours, and whether it’s even possible with such a short turnaround time, then combining a keto diet with intermittent fasting is a must. I am a massive advocate of not only the ketogenic diet but also the practice of daily fasting – I swear by it! It’s not for everyone as it does require a lot of discipline to pull off. But if you can commit to it, the benefits in my opinion are well worth it. So you may be wondering what intermittent fasting is? Well, it’s the practice of performing a daily fast from food and (caloric) drinks for at least 16 hours of the day.

Ketone Esters: These are not normally found in the body, but exogenous ketone esters convert into BHB once it is in the body. They are also synthetically (lab) made compounds that link an alcohol to a ketone body, which can then be metabolized by the liver into a ketone. They are like ketone salts on steroids as they have 5-10 time more BHB per serving/maximum daily intake than ketone salts. To date, pure ketone esters have been very expensive to produce and have only been available to researchers, elite athletes (Tour de France cyclists), and the US Department of Defense (people have spent more than $20,000 to have an independent lab produce a single serving!).


For the first part of my experiment, I would simply record my blood ketone and glucose levels over a period of two hours after taking the ketone esters. While I am already fairly keto-adapted and can attain nutritional ketosis fairly easily (> 0.5 mmol/L), it wasn’t until the end of my Five-day Fasting Mimicking Diet that I was even close to reaching therapeutic ketosis levels (>5.0 mmol/L).
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?
The liver is always producing ketones to some small degree and they are always present in the bloodstream. Under normal dietary conditions, ketone concentrations are simply too low to be of any significant benefit. A ketogenic diet and exogenous ketone supplements will increase the amount of ketone in your body. The idea that ketones are “toxic” is ridiculous. Ketones are a normal physiological substance that play many important roles in the human body.
There is also evidence that individuals who adhere to a low-carbohydrate or ketogenic diet may require higher sodium intakes. Due to their low carbohydrate contents, these diets reduce insulin levels. Since one of insulin’s roles is to decrease the excretion of sodium in the urine[7], low-carbohydrate and ketogenic dieters excrete more sodium than normal, and are encouraged to salt their meals to increase their sodium intake.
Too low of sodium intake can be just as dangerous as getting too much. As with all essential nutrients, the graph for risk associated with sodium and health problems is actually u-shaped, such that both low and high quantities of sodium are associated with risk of cardiovascular disease and all-cause mortality[8]. Evidence also suggests that restricting sodium to the recommendations may rapidly increase plasma levels of renin, angiotensin II, and aldosterone, which can lead to complications in itself[9].
Calories do matter, even on a ketogenic diet. If you consume more calories than your body uses, you’re going to gain weight. Period. What you mean to say is that it’s very difficult to eat your entire day’s worth of calories on a ketogenic diet because fats are so satiating. This distinction is important to keep in mind for those who generally have a voracious appetite (like me).
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).
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.

Other ingredients: Many of the supplements contain large amounts of caffeine – the supplement we tested from Prüvit contains the same amount as a 16 oz cup of coffee! Some supplements also contain malic acid, which is “known for its ability to increase energy and tolerance to exercise”. This leaves the nagging doubt: if the experiment shows an increase in energy and physical performance, for example, how do we know it is the (expensive) BHB causing the effect and not the (inexpensive) other ingredients?


Venous blood samples (2 ml) were obtained during all visits using a 22 G catheter inserted percutaneously into an antecubital vein. The catheter was kept patent using a saline flush following each sample collection. Additionally, during Study 1, arterialized blood from a catheter inserted into a heated hand (Forster et al., 1972) was collected into heparinized blood gas syringes (PICO 100, Radiometer, Copenhagen) from a subset of participants (n = 7) and immediately analyzed for pH and electrolytes using a clinical blood gas analyser (ABL, Radiometer, Copenhagen).
If you do the same calculations as I did above for estimating fat oxidation, you’ll see that EE in this case was approximately 13.92 kcal/min, while fat oxidation was only 67% of this, or 9.28 kcal/min, or 1.03 g/min. So, for this second effort (the test set) my body did about 5% less mechanical work, while oxidizing about 25% less of my own fat. The majority of this difference, I assume, is from the utilization of the exogenous BHB, and not glucose (again, I will address below what I think is happening with glucose levels).

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