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).
To be in ketosis, you need to get very specific about the macronutrient ratios hanging off your fork. This means eating 75% fats, 20% protein and 5% carbohydrates. It’ll see you getting 5-10% of your total calories from carbohydrates, which is roughly 25-30g of carbs per day, and diligently keeping this below the 50g threshold creates the ketosis that burns stored fat. Unlike the no-limit-protein option on the table when going low carb, eating more than 0.67-0.81g of protein per pound of bodyweight can hoof you out of ketosis because too much of it can be converted into glucose, blunting the benefits of the ketones. On the plus side, you will have a high fat intake, making your energy levels more balanced so you can train at higher intensities.
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.
Methods and Results: In the first study, 15 participants consumed KE or KS drinks that delivered ~12 or ~24 g of βHB. Both drinks elevated blood D-βHB concentrations (D-βHB Cmax: KE 2.8 mM, KS 1.0 mM, P < 0.001), which returned to baseline within 3–4 h. KS drinks were found to contain 50% of the L-βHB isoform, which remained elevated in blood for over 8 h, but was not detectable after 24 h. Urinary excretion of both D-βHB and L-βHB was <1.5% of the total βHB ingested and was in proportion to the blood AUC. D-βHB, but not L-βHB, was slowly converted to breath acetone. The KE drink decreased blood pH by 0.10 and the KS drink increased urinary pH from 5.7 to 8.5. In the second study, the effect of a meal before a KE drink on blood D-βHB concentrations was determined in 16 participants. Food lowered blood D-βHB Cmax by 33% (Fed 2.2 mM, Fasted 3.3 mM, P < 0.001), but did not alter acetoacetate or breath acetone concentrations. All ketone drinks lowered blood glucose, free fatty acid and triglyceride concentrations, and had similar effects on blood electrolytes, which remained normal. In the final study, participants were given KE over 9 h as three drinks (n = 12) or a continuous nasogastric infusion (n = 4) to maintain blood D-βHB concentrations greater than 1 mM. Both drinks and infusions gave identical D-βHB AUC of 1.3–1.4 moles.min.
One thing to remember here is that even if your calculated daily ‘keto approved’ protein allowance is (let’s say) 150g, that doesn’t mean you can eat 150g in one meal and still be in ketosis. You may find that you can’t eat more than 40g of protein at a time, otherwise you will drop out of ketosis. OR, you may find you can eat 50g of protein but you need a LOT of fat. Whereas a small serve of 15g of protein without fat might knock you out of ketosis.
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 final graph, below, shows the continuous data for only VO2 side-by-side for the 20 minute period. The upper (blue) line represents oxygen consumption under control conditions, while the lower line (red) represents oxygen consumption following the BHB ingestion. In theory, given that the same load was being overcome, and the same amount of mechanical work was being done, these lines should be identical.
In a subset of participants (n = 7) the effect of 3.2 mmol.kg−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).
Currently, we lack enough evidence to change the recommendations for calcium intake. The Tolerable Upper Intake Level (UL) for adults 19-50 years old is 2500 mg. This is well over the RDA of 1000 mg for the same age group. Calcium supplements commonly contain 600-1200 mg. When assessing your own calcium intake, keep in mind that calcium from food sources and calcium from supplements may have different outcomes.
Measurements taken included whole blood glucose and BHB (every 5 minutes); VO2 and VCO2 (every 15 seconds); HR (continuous); RQ is calculated as the ratio of VO2 and VCO2. In the video of this post I explain what VO2, VCO2, and RQ tell us about energy expenditure and substrate use—very quickly, RQ typically varies between about 0.7 and 1.0—the closer RQ is to 0.7, the more fat is being oxidized; the reverse is true as RQ approaches 1.0
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*:
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.
Think about it like building muscle, good supplements can enhance your results, but if you don't eat right and exercise, supplements are just useless. You can't just sit on the couch to watch TV, eat potato chips all day and drink some supplements and expect to gain muscle. A supplement is not a miracle. It's just an addition and before you add it to your diet, you need to get the basics right first, which is dieting and exercise in the case of building muscles. The supplements are not going to lift the heavy weights for you. You do!
I have tried the following preparations of exogenous ketones: BHB monoester, AcAc di-ester, BHB mineral salt (BHB combined with Na+, K+, and Ca2+). I have consumed these at different concentrations and in combination with different mixing agents, including MCT oil, pure caprylic acid (C8), branch-chained amino acids, and lemon juice (to lower the pH). I won’t go into the details of each, though, for the sake of time.
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