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!
Exogenous ketones are ketones that come in the form of a powder that you mix with water to drink them. Exogenous ketones are controversial in the keto world. The problem is the marketing of them have made some people believe that all they have to do is use this product to get into ketosis. If your blood glucose is too high your body will not use the ketones and they will go to waste.
As repeated KE consumption would be required to maintain nutritional ketosis, we investigated the kinetics of drinks in series and of continuous intra-gastric infusion. During starvation, the accumulation of ketones (>4 mM) reportedly inhibited ketone clearance from the blood, however the underlying mechanism is unknown (Hall et al., 1984; Wastney et al., 1984; Balasse and Fery, 1989). In Study 3, βHB uptake and elimination were identical for the second and third KE drinks, suggesting that βHB may have reached a pseudo-steady state should further identical boluses have been given at similar intervals. Furthermore, when the KE was given at a constant rate via a NG tube, blood ketone concentrations remained ~3 mM. Therefore, repeated KE drinks effectively maintain ketosis at the intervals and doses studied here.
I’m often asked if it’s necessary to buy and use keto products like urine sticks. They’re small test strips that you dip in urine to see if your body is producing ketones (and therefore indicate if you’ve entered ketosis.) There's very little information on how to know that you are in ketosis other than using these ketones supplements because they are as accurate as can be in determining your current state. Outside of that, you can only guess if you are in it or not by your body's performance.
Here we investigated the effects of KE and KS consumption on blood βHB and metabolite concentrations. As we found that KE ingestion delivered a >50% higher plasma concentrations of d-βHB alone, we subsequently determined the reliability and repeatability of ketosis following KE consumption and the effects of concomitant meal ingestion on blood ketone and substrate kinetics. Finally, we determined whether nasogastric infusion could be used for KE administration, given that some patients require feeding in this manner.
I followed 30g carbs as my limit each day, moderate protein, increased fat intake (avocado at each main meal plus carefully chosen oils, eggs and nuts) and have upped green veg to the bucket load and incorporated a juiced lemon in water to my morning, as well as my usual water consumption. I also did intermittent fasting Mon to Thur, 18 hours fasting each day.
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.
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).
Baseline measurements showed no significant changes in triglycerides or the lipoproteins (data not shown). Data represent triglyceride and lipoprotein concentrations measured after 4 weeks of daily exogenous ketone supplementation. No significant change in total cholesterol was observed at 4 weeks for any of the ketone treatment groups compared to control. (Fig. 1a). No significant difference was detected in triglycerides for any ketone supplement compared to control (Fig. 1b). MCT supplemented animals had a significant reduction in HDL blood levels compared to control (p < 0.001) (Fig. 1c). LDL levels in ketone-supplemented animals did not significantly differ from controls (Fig. 1d).
In a keto-adapted individual where ketone metabolism is brisk with up to 100 grams or more being oxidized (i.e., ‘burned for energy’) daily, the small amount lost in breath and urine as acetone is minor. But because this breakdown occurs spontaneously without needing the help of enzymes, it also happens to AcAc in a stored beverage or food (even in an air-tight container), making the shelf-life of AcAc-containing products problematic. Thus all current ketone supplements consist of BOHB in some form rather than the naturally occurring mix of BOHB and AcAc produced by the liver.
We’ve all been taught that high sodium intake is bad for us, similar to how we’ve been told for decades that fat is the driver of coronary heart disease, and consuming large amounts will kill us. Sodium has been thought to increase blood pressure, and therefore increase the risk of heart disease, kidney disease, stroke, osteoporosis, and stomach cancer. Thus, many of us tend to avoid consuming foods or supplements with labels that have high amounts of sodium.
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)
The chart below shows my ketone and glucose response to consuming 40g of KetoneAid’s ketone esters, which had been calculated to be my optimal serving size based on my weight (170lbs) and type of activity (I am moderately active/athletic, but cognitive experiments are a “low” physical activity). Normally, for increased physical performance ketone esters are consumed along with some glucose, but since I was only focusing on cognitive performance I did not consume any glucose.
Supplemental BHB’s are ideal for people new to the ketogenic way of eating. The changes that happen in your brain and body when adapting to a VLC diet are both immediate and profound. For example, our kidney’s start processing minerals salts much more efficiently. Ironically, after years of being advised to decrease our intake of salt (sodium), it turns out that for people transitioning away from the Standard American Diet (SAD diet) towards a lower carb or ketogenic diet there is actually a need to increase dietary mineral salts such as potassium, sodium, magnesium and calcium. During the process of becoming keto-adapted, it is very important to increase your intake of these essential minerals, in order to prevent the onset of unpleasant symptoms (known as “keto flu”).
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 . 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 . Children typically remain on the diet for approximately two years then return to a diet of common fat and carbohydrate ingestion . 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 .
If the color is close to the original beige of the test strip, it means there are few if any ketones in your urine and you’ll need to make some dietary tweaks. This may include eating less fat. That’s because if you have doubled down on the healthy fats your body may be rebelling. One way to tell is if you are constipated. If you think this is the case, ratchet back the fats by 50% and see if it makes a difference.
In the second of these posts I discuss the Delta G implications of the body using ketones (specifically, beta-hydroxybutyrate, or BHB, and acetoacetate, or AcAc) for ATP generation, instead of glucose and free fatty acid (FFA). At the time I wrote that post I was particularly (read: personally) interested in the Delta G arbitrage. Stated simply, per unit of carbon, utilization of BHB offers more ATP for the same amount of oxygen consumption (as corollary, generation of the same amount of ATP requires less oxygen consumption, when compared to glucose or FFA).
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