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).
KE was synthesized as previously described [29]. BMS is a novel agent (sodium/potassium- βHB mineral salt) supplied as a 50 % solution containing approximately 375 mg/g of pure βHB and 125 mg/g of sodium/potassium. Both KE and BMS were developed and synthesized in collaboration with Savind Inc. Pharmaceutical grade MCT oil (~65 % caprylic triglyceride; 45 % capric triglyceride) was purchased from Now Foods (Bloomingdale, IL). BMS was formulated in a 1:1 ratio with MCT at the University of South Florida (USF), yielding a final mixture of 25 % water, 25 % pure βHB mineral salt and 50 % MCT. BD was purchased from Sigma-Aldrich (Prod # B84785, Milwaukee, WI).
Geek note: Technically speaking, beta hydroxybutyrate is NOT a legitimate ketone body. Ketone bodies, or ketones are technically molecules with carbonyl carbons which are bonded to two additional carbon atoms. One carbon has four available bonds. When that carbon is double bonded to oxygen and also has two single bonds to carbon, we have a ketone body. If you have a carbon atom that is double bonded to an oxygen (carbonyl group), which is also bound to an -OH group instead of two different carbon atoms, that would be a carboxylic acid, but that really doesn’t matter in this case. For all intents and purposes of the ketogenic diet, betahydroxybutyrate should be considered one of the three ketone bodies and a “ketone” nonetheless. Your body uses BHB pimarily for energy in the state of ketosis, so it’s a ketone, okay?
Another effect of the ketone drinks was to lower blood glucose, free fatty acids, and triglyceride levels. This sounds great. Elevated levels of all those markers are harbingers of disease, particularly if they remain chronically elevated. But think about what this means. If free fatty acids go down, that means adipose tissue isn’t being liberated for burning.
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.
Keto dieters love exogenous ketones because they help fight the keto flu and get you quickly into ketosis. One study found that taking drinks with exogenous ketones lowers blood levels of glucose, free fatty acid, and triglycerides [8]. The study concluded that exogenous ketones are a practical and effective way to achieve ketosis. Taking exogenous ketones longer will also speed up the process of keto-adaptation.
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).

There’s some support that exogenous ketones can be helpful for people already dutifully following the keto diet — but research has been limited. One thing we know for sure: These aren’t a get-thin-quick solution. “I think people are drawn to a quick, easy fix, kind of a magic bullet supplement, and it’s not that this won’t contribute to weight loss, but it’s not that magic bullet,” Griffin says.

Response inhibition is the ability to suppress inappropriate responses that interfere with goal-directed actions. Two cards are shown, one above the other, each containing the name of a color in a certain color. The goal is to rapidly indicate if the meaning of the color on top (i.e. “yellow”) matches the color of the color on the bottom (i.e., card says “red” but is colored yellow).

The current recommendation for magnesium is 310-320 mg for adult women and 400-420 mg for adult men. Magnesium deficiencies are common; 2005-2006 data indicates that the majority of Americans’ dietary magnesium intake was less than the Estimated Average Requirement (EAR) for the respective age groups[25]. The EAR for a nutrient is about 20% LESS than the RDA. Current data on magnesium intake and deficiency in the US is not readily available, as magnesium testing is not part of routine electrolyte testing in hospitals and clinics[26].

Besides cutting carbs, it's important to increase your fat intake, and be moderate with protein. The fat you eat will keep you feeling energized and support ketone production. Protein is also important but if you go overboard with it, your body could enter into a process called gluconeogenesis. In gluconeogenesis, your body makes glucose from protein, and you want to avoid that.

Keto-adaption is a complex set of metabolic processes in which the body shifts from using primarily glucose for energy to using largely ketones and fat for energy. Achieving ketosis doesn’t mean the body is maximizing the use of these ketones; it takes longer than a few days for the body to get used to burning fat and ketones as its predominant fuels.
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
I’m getting an increasing number of questions about exogenous ketones. Are they good? Do they work for performance? Is there a dose-response curve? If I’m fasting, can I consume them without “breaking” the fast? Am I in ketosis if my liver isn’t producing ketones, but my BOHB is 1.5 mmol/L after ingesting ketones? Can they “ramp-up” ketogenesis? Are they a “smart drug?” What happens if someone has high levels of both glucose and ketones? Are some products better than others? Salts vs esters? BHB vs AcAc? Can taking exogenous ketones reduce endogenous production on a ketogenic diet? What’s the difference between racemic mixtures, D-form, and L-form? What’s your experience with MCTs and C8?

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