It’s not clear that the Weir coefficients used to estimate EE are relevant for someone in ketosis, let alone someone ingesting exogenous BHB. (The Weir formula states that EE is approximated by 3.94 * VO2 + 1.11 * VCO2, where VO2 and VCO2 are measured in L/min; 3.94 and 1.11 are the Weir coefficients, and they are derived by tabulating the stoichiometry of lipid synthesis and oxidation of fat and glucose and calculating the amount of oxygen consumed and carbon dioxide generated.) While this doesn’t impact the main observation—less oxygen was consumed with higher ketones—it does impact the estimation of EE and substrate use.

All of the data I’ll present below were from an experiment I did with the help of Dominic D’Agostino and Pat Jak (who did the indirect calorimetry) in the summer of 2013. (I wrote this up immediately, but I’ve only got around to blogging about it now.) Dom is, far and away, the most knowledgeable person on the topic of exogenous ketones. Others have been at it longer, but none have the vast experiences with all possible modalities (i.e., esters versus salts, BHB versus AcAc) and the concurrent understanding of how nutritional ketosis works. If people call me keto-man (some do, as silly as it sounds), they should call Dom keto-king.

Exogenous ketones have a wide range of benefits that can enhance your fat-burning lifestyle. I personally use them daily as a strategy to heighten my mental performance and give my workouts an extra boost. For these purposes, I have also found it logical to combine exogenous ketones with other known health and performance boosting agents such as branched-chain amino acids and medicinal mushrooms.
But there have also been studies done showing that the Inuit Eskimo’s do not actually reach a state of ketosis. This is due to numerous factors. One being that the diet the eskimo’s eat ‘would not be expected to cause ketosis, because the calculated anti-ketogenic effect of the large protein ingestion was somewhat more than enough to offset the ketogenic effect of fat plus protein.” 
Exogenous ketones are not a shortcut to nutritional ketosis, but they do give your body a break from full-time carb usage. They are a tool you can use to get into ketosis if your lifestyle makes it too difficult to do so without them. And they’re also a good way to get an increased edge for those who are very on top of their nutrition and performance.
That’s exactly what ketones do: inhibit lipolysis, the breakdown of body fat into triglycerides and free fatty acids for burning. In normal conditions where ketones are produced endogenously, this is expected and beneficial. If homemade ketones increased lipolysis, you’d end up with ketoacidosis. You’d make ketones which released more body fat which got turned into more ketones which released more body fat which became more ketones. And on and on. It simply wouldn’t stop.

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.
Ketones are also a cleaner-burning fuel than carbs. They’re burned for energy in the mitochondria, and fewer free radicals (a highly-reactive, short-lived uncharged molecule) are generated when compared to burning glucose.15 What’s more, ketone molecules themselves cause a decrease in production of free radicals,21,22 while also increasing glutathione–a powerful antioxidant protecting against mitochondrial damage induced by free radicals.23
Lots of good info but some things are just plain wrong. It takes 2 days max to get into ketosis if you stop eating carbs. Your body can only store roughly 2 days worth of glycogen. When those stores are exhausted your body will immediately turn to fat. It may take a week or several weeks to get “keto adapted” but it simply won’t ever take you more than 2 days to get into a state of ketosis.
What is the reason for needing to keep our stress levels down? Well the body reacts to stress, whether physical or emotional, by dumping glycogen and potentially glucose in your bloodstream, thus elevating insulin levels. This in turn blocks our bodies from entering ketosis. To keep your mental and emotional stress to a minimum, it may be wise to meditate, sleep, relax, or do something that is fun and care-free.
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.
My two cents: I wouldn’t take ketone supps if not on some sort of low(ish) carb diet because the idea of high levels of BOTH fuels (ie, ketones AND glucose) doesn’t seem physiologically appropriate… more like a recipe for disaster, and by “disaster,” I mean “out-of-control production of Reactive Oxygen Species” — this might not matter if you’re an athlete looking for a quick performance boost, because the fuels are going to be cleared rather quickly… not so much if you’re a desk jockey.
In a subset of participants (n = 7) the effect of 3.2−1 of βHB as KE and KS on blood pH and electrolytes after ketone drinks was investigated. Blood d-βHB kinetics were similar to those in the initial experiment (Figure ​(Figure3A).3A). After 60 min, blood pH declined from 7.41 to 7.31 following a KE drink (p < 0.001, Figure ​Figure3B).3B). Bicarbonate fell significantly from 23.6 ± 0.7 to 17.0 ± 0.8 mM following KE drinks (p < 0.001), but remained within the normal range (Figure 3C). Both ketone drinks significantly decreased blood potassium concentrations by 0.7 mM (both drinks p < 0.05, Figure 3D) and increased sodium and chloride concentrations (Sodium: both drinks p < 0.05, Chloride: KE = p < 0.05, KS = p < 0.005, Figures 3E,F).
Some people follow more of an Ultra Low Carb diet approach. This is generally around 50g or less of carbs per day. A ULC is more supportive of reaching a ketogenic state, but again total carbs are not the only variable when it comes to reaching ketosis (other factors such as types of carbs, protein consumption, portion size, ingredients, supplements used etc. all play a role and will be covered in more detail below). 

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.
So if your high-fat diet includes a high amount of roasted seeds or roasted nuts, nut butters, heated oils such as heated coconut oil or heated extra virgin olive oil, barbecued meats or meats cooked at very high temperatures, then your triglyceride count is going to go up. You should have triglycerides that are less than 150mg/dL, and a triglyceride to HDL ratio that is no more than 4:1, and in most of the healthiest people I’ve worked with, triglycerides are under 100 and the triglyceride to HDL ratio is less than 2:1. If your ratio is whacked, your ketogenic diet isn’t doing you any favors.’
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. 
A common question is why BHB is the go-to ketone body for exogenous ketone supplements. The likely reason is a combination of its efficient conversion into energy and its ease of formulation. In other words, that it is easier to formulate BHB into a nutritional supplement. And the body efficiently converts BHB to acetoacetic acid, which effectively raises blood ketone levels.
This is an excellent resource. Thank you for all the work and resources you found. i had never even heard of Adkins 72. I am keto but I always let Sunday be my high Carb cheat day.So im learning from this blog how to get back in ketosis in 24 hours after my 4pm meal on Sunday The Lords & family day. So im 25hr fasting. I would like to reference this article on my blog, thanks for helping me on my 100 lb lost journey.
A lot of people who use ketogenic diets will include a regular (i.e. weekly) carb refeed meal. There are various reasons behind doing this. If you are doing a lot of glycolic based training, then the carb refeed can help bump up muscle glycogen levels and in turn boost performance. Others use these refeeds as a way to keep their thyroid health in check, and finally some people use these refeeds as a ‘cheat day’ – so that they can still enjoy the pleasures from carbohydrates!
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.
Remember how important it is to measure ketone blood levels accurately? Same goes for food tracking. A food tracking app, like MyFitnessPal, provides insight into macronutrient intake and thus the ability to tweak the diet to achieve ketosis. Tracking diet (inputs) and measuring ketones levels (outputs) delivers the best shot at optimizing the keto diet plan.
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.
Glucose and BHB went down slightly throughout the effort and RQ fell, implying a high rate of fat oxidation. We can calculate fat oxidation from these data. Energy expenditure (EE), in kcal/min, can be derived from the VO2 and VCO2 data and the Weir equation. For this effort, EE was 14.66 kcal/min; RQ gives us a good representation of how much of the energy used during the exercise bout was derived from FFA vs. glucose—in this case about 87% FFA and 13% glucose. So fat oxidation was approximately 12.7 kcal/min or 1.41 g/min. It’s worth pointing out that “traditional” sports physiology preaches that fat oxidation peaks in a well-trained athlete at about 1 g/min. Clearly this is context limited (i.e., only true, if true at all, in athletes on high carb diets with high RQ). I’ve done several tests on myself to see how high I could push fat oxidation rate. So far my max is about 1.6 g/min. This suggests to me that very elite athletes (which I am not) who are highly fat adapted could approach 2 g/min of fat oxidation. Jeff Volek has done testing on elites and by personal communication he has recorded levels at 1.81 g/min. A very close friend of mine is contemplating a run at the 24 hour world record (cycling). I think it’s likely we’ll be able to get him to 2 g/min of fat oxidation on the correct diet.

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