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).
Plasma glucose, free fatty acids (FFA), triglycerides (TG) and urinary d-βHB were assayed using a commercial semi-automated bench-top analyzer (ABX Pentra, Montpellier, France), and insulin was measured using a commercially available ELISA assay (Mercodia, Uppsala, Sweden). Both the pure liquid KS and KE, and a subset of plasma (n = 5) and urine (n = 10) samples from a subset of participants in Study 1 underwent analysis using GC-MS and a chiral column, and the concentrations of l-βHB was calculated using the enzymatically determined concentration of d-βHB and the ratio of the d/l-βHB peaks obtained through GC-MS. Acetoacetate was assayed using an enzymatic method (Bergmeyer, 1965), and breath acetone was measured using GC-MS (Study 1) or with a handheld electrochemical device (Study 2; NTT DOCOMO, Japan) (Toyooka et al., 2013).
Exogenous ketones are becoming more popular as advancements in scientific research continue to show how they work to improve both health and performance. At first, the only options for delivering exogenous ketones were unpalatable ketone esters; however, exogenous ketones can now be taken in the form of ketone mineral salts that are more palatable and easily blended in water. Making ketone mineral salts involves combining beta-hydroxybutyrate (BHB) with mineral salts such as sodium, calcium, magnesium, or potassium. Before considering whether ketone supplements are a good option, most people immediately look at the salt load, and rightfully so. It is important to take into account the nutritional and health impact of not only the BHB but the minerals that are used to make the product.
While the KetoneAid folks have been seeing tremendous success working with elite athletes to improve athletic performance, I thought it would be interesting to quantify the effects of ketone esters on cognitive performance. For the week prior to taking the ketones, I re-established baseline scores in a number of cognitive testing areas using Lumosity*:
Plecko B., Stoeckler-Ipsiroglu S., Schober E., Harrer G., Mlynarik V., Gruber S., et al. . (2002). Oral beta-hydroxybutyrate supplementation in two patients with hyperinsulinemic hypoglycemia: monitoring of beta-hydroxybutyrate levels in blood and cerebrospinal fluid, and in the brain by in vivo magnetic resonance spectroscopy. Pediatr. Res. 52, 301–306. 10.1203/01.PDR.0000019439.27135.2B [PubMed] [CrossRef]
Interestingly, the effects of exogenous ketones on blood substrate concentrations were preserved with the metabolic stimulus of a mixed meal. Following KE drinks, FFA and glucose fell and remained low in both fed and fasted subjects, despite higher insulin throughout the fed arm, suggesting that there was no synergistic effect of insulin and βHB to further lower blood glucose or FFA. In agreement with previous work, the threshold for the effects of βHB on glucose and lipids appears to be low (<1 mM), as there was no significant dose-response relationship between increasing blood βHB and the small changes in plasma FFA, TG or glucose across all of the study drinks (Mikkelsen et al., 2015).
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.
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.

As KE drinks achieved a significantly higher d-βHB concentrations than KS, we investigated factors that may be important in the use of ketone drinks to achieve nutritional ketosis. Initially we determined the repeatability of blood ketosis following KE drinks and found little variation in kinetic parameters between individuals. Variability between participants was less than within the population, and accurate individual prediction of the d-βHB Cmax following a body-weight adjusted KE drink was achieved. Variability within individuals was likely due to normal daily changes in GI function, including gastric emptying, portal blood flow or intestinal transit time, which may alter KE hydrolysis and absorption.
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.
Getting into a state of ketosis normally involves eating a ketogenic diet consisting of around 80 percent fat, 15 percent protein, and 5 percent carbs. Over time, the body transitions from burning carbs for fuel to burning ketones—an alternative fuel source that the liver makes by breaking down fat, explains keto diet expert Amy Davis, RD, LDN. Since advocates say that ketosis can help you lose weight fast, think more clearly, and feel more energized, it’s tempting to try.
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.

Exogenously delivered ketone supplements significantly altered rat weight gain for the duration of the study (Fig. 6). However, rats did not lose weight and maintained a healthy range for their age. Rats have been shown to effectively balance their caloric intake to prevent weight loss/gain [97–99]. Due to the caloric density of the exogenous ketone supplements (Table 1) it is possible for the rats to eat less of the standard rodent chow and therefore less carbohydrates while maintaining their caloric intake. Food intake was not measured for this study. However, if there was a significant carbohydrate restriction there would be a signifcant change in basal blood ketone and blood glucose levels. As the hallmark to the KD, carbohydrate restriction increases blood ketone levels and reduces blood glucose levels. Neither an increase in basal blood ketone levels nor a decrease in basal blood glucose levels was observed in this study (Fig. 7). Additionally, if there were an overall blood glucose decrease due to a change in food intake, this would not explain the rapid reduction (within 30 min) in blood glucose correlated with an elevation of blood ketone levels after an intragastric bolus of ketone supplement (Figs. 2, ​,33 and ​and44).
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 shred weight in their sleep. Seriously... how is that even scientifically possible. So if you are thinking about trying out a particular supplement, I would suggest two things:
At baseline, 4 h after intragastric gavage, the elevation of blood ketones was inversely related to the reduction of blood glucose compared to controls following the administration of MCT (5 g/kg) (p = 0.008) and BMS + MCT (5 g/kg) (p = 0.039) . There was no significant correlation between blood ketone levels and blood glucose levels compared to controls for any other ketone supplemented group at baseline (Fig. 4a). At week 4, 4 h after intragastric gavage, there was a significant correlation between blood ketone levels and blood glucose levels compared to controls in MCT (10 g/kg) and BMS + MCT (10 g/kg) (p < 0.0001, p < 0.0001) (Fig. 4b).
Obviously, cutting carbs is much easier than not eating anything at all for days on end. It's also safer for people with diabetes as it leads to a gradual decline in blood glucose [2]. The carbs you have to reduce are known as net carbs. Those are the carbs that your body uses to make glucose. You calculate them by subtracting the grams of fiber from total carbs in a food item.
You see, when someone says ketosis is a natural state, they mean that ketosis is the body’s backup plan for those times when there isn’t any food to eat. It’s an evolutionary adaptation that developed over hundreds of thousands of years and springs from a time when our distant ancestors often had to go many days between decent meals. Fortunately, these days actual starvation is pretty rare so most people will never be in ketosis. But the physiological mechanism is still there, lurking in the background, readily accessible to anyone who is willing to trick their body into thinking it’s starving.
Intermittent fasting involves merely changing your eating cycle whereby you prolong the period in which you will have your first meal. This diet plan helps to create a smaller eating window. In doing so, it means that you will consume less amount of calories. In addition to depriving the body some calories, intermittent fasting forces the body to begin burning fats. It does so to compensate for the current deficiency.
Directions — — As a dietary supplement, mix 1 scoop of ketone powder with 8-12 oz of water To avoid gastrointestinal discomfort, start with 1/2 scoop (or even less) and gradually increase to a full serving. Best consumed prior to exercise to enhance performance. Do not exceed 3 scoops per day. As a dietary supplement take 1 serving of PX Ketotropin twice daily. Ideally the 1st servings (4 capsules) should be taken prior to the first meal of the day. Consume 2nd serving 30 minutes prior to strenuous physical activity. If no physical activity is performed please consumer 2nd serving prior to afternoon meal. Additional servings can be taken in between meals throughout the day if needed. Do not consume more than 6 servings of PX Ketotropin
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.
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)!

Personally, I think it is wise to include a regular carb meal in your diet if you are going to follow a ketogenic diet. Long term ketogenic diets do seem to downregulate your thyroid and metabolism, and a weekly carb meal (or carb day) can help avoid this. The Carb Nite diet by J. Kiefer is a good example of this. And BJJCaveman posted his labs showing how a weekly carb meal helped his thyroid HERE.
Again, there are very interesting animal studies plus some single case reports and small uncontrolled trials of humans with neurodegenerative disease and cancer given ketogenic diets and/or exogenous ketones (Murray 2016, Poff 2015, Roberts 2017, Newport 2015, Cunnane 2016). In some cases where the patient does not have the cognitive resources to comply with a well-formulated ketogenic diet, or where target blood levels of BOHB that work in animals are hard to achieve in humans by diet alone, supplemental ketones may have an important role to play in the prevention, management, or reversal of these disease categories.
I wrote this post at about the same time Germany won the World Cup in Rio de Janeiro in 2014. There’s been a lot of moving and shaking in the world of exogenous ketones since then, not to mention soccer. Looking back on my post, I still consider it relevant in terms of what exogenous ketones possibly can (and cannot) do for performance. In this case, to see if exogenous ketone esters provide me a “boost” by allowing me to do the same amount of work while expending less energy (and work at a relatively lower VO2) compared to no supplementation.

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