The other potentially important distinction between nutritional ketosis and chemically-induced ketosis is the potential metabolic role played by liver AcAc production and redox status. Although the ratio of BOHB to AcAc in venous blood is typically 80% to 20%, classic studies by Cahill (1975) have observed important hepatic vein and peripheral arterio-venous gradients for this ratio in keto-adapted patients. What these observations imply is that the liver produces a higher proportion of AcAc than is found in the peripheral blood, and that this is due to uptake of AcAc in peripheral cells (principally muscle) with re-release as BOHB. In the process, the reduction of AcAc to BOHB produces NAD+, which is beneficial to mitochondrial redox state and mitochondrial function (Verdin 2015, Newman 2017).

The metabolic phenotype of endogenous ketosis is characterized by lowered blood glucose and elevated FFA concentrations, whereas both blood glucose and FFA are lowered in exogenous ketosis. During endogenous ketosis, low insulin and elevated cortisol increase adipose tissue lipolysis, with hepatic FFA supply being a key determinant of ketogenesis. Ketone bodies exert negative feedback on their own production by reducing hepatic FFA supply through βHB-mediated agonism of the PUMA-G receptor in adipose tissue, which suppresses lipolysis (Taggart et al., 2005). Exogenous ketones from either intravenous infusions (Balasse and Ooms, 1968; Mikkelsen et al., 2015) or ketone drinks, as studied here, inhibit adipose tissue lipolysis by the same mechanism, making the co-existence of low FFA and high βHB unique to exogenous ketosis.
No this is wrong. Your body will use your own fat and any fat you eat as fuel. This counts as exogenous ketones. It won’t stop burning your fat. The same logic would say that if eating any fat your fat loss would stall and that is not true. It can help get you back into ketosis because you have certain monocarboxylic acid transporters that are upregulated when ketones are present. The evidence is physiology.
Exogenous ketones supplements is also necessary if you’re wondering how to get into ketosis in 24 hours. Directly ingesting ketones via salts or esters will boost blood ketone levels in the system. These are generally made up of beta-hydroxybutyrate (BHB) which is processed by the body to metabolise into ketones for energy. Some benefits of taking such supplements include anti-inflammatory properties, cancer prevention, increased cognitive function, weight-loss, and athletic performance enhancement.
It comes in a small bottle that usually contains 50-100 strips depending on the type you choose. It’s very thin, and on one end there’s a small square of paper (this is the end you dip in the urine). If there are ketones in your urine, the little paper will change color. The darker it is (light pink up to a purple color) the more it is in your urine. On the bottle, there’s a picture you compare the color of the paper with that can be a very good indication of your current ketone state. 
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).
Proponents like Heverly say that taking exogenous ketones can transform your body—and your life. (Her before-and-after shots below were taken just 10 days apart.) “Within 10 days, my body had this shift. My midsection wasn’t as bloated or fluffy. And I don’t have that cellulite on my legs now,” she says. Heverly also credits Prüvit with giving her a much-needed energy boost and improved mental clarity.
After a few days of fasting, or of drastically reduced carbohydrate consumption (below 50 g/day), glucose reserves become insufficient both for normal fat oxidation via the supply of oxaloacetate in the Krebs cycle (which gave origin to the phrase ‘fat burns in the flame of carbohydrate') and for the supply of glucose to the central nervous system (CNS).4

Ketosis is a unique metabolic state where your body burns fat instead of glucose for fuel. Glucose is a simple sugar molecule derived from carbohydrates. Your body prefers using glucose to using fat and protein to make energy. This is because glucose it is easy to burn as it doesn't require much energy. On the other hand, your body uses fat and protein to build and repair tissue and make hormones.
The effects of the two exogenous ketone drinks on acid-base balance and blood pH were disparate. In solution the ketone salt fully dissociates (giving a total of 3.2–6.4 g of inorganic cation per drink), allowing βHB− to act as a conjugate base, mildly raising blood and urine pH, as seen during salt IV infusions (Balasse and Ooms, 1968; Balasse, 1979). Urinary pH increased with the salts as the kidneys excreted the excess cations. In contrast, KE hydrolysis in the gut provides βHB− with butanediol, which subsequently underwent hepatic metabolism to form the complete keto-acid, thus briefly lowering blood pH to 7.31. Electrolyte shifts were similar for both KE and KS drinks and may have occurred due to βHB− metabolism, causing cellular potassium influx and sodium efflux (Palmer, 2015).

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!
Unless otherwise stated, statistical analysis was conducted using Prism 6™ software. Values, expressed as means ± SEM, were considered significantly different at p < 0.05. Initial tests were undertaken to ensure that normality and sphericity assumptions were not violated. Subsequently, either one or two way repeated measures ANOVA, or Freidman's test with post-hoc Tukey or Dunnet's correction were performed, to compare changing concentrations of substrates, electrolytes, pH, insulin, breath and urinary βHB: both over time and between study interventions. In Study 2, data from each of the two study visits in each condition (fed and fasted) completed by an individual were included in the analysis.
Caveat emptor: the following post doesn’t come close to answering most of these questions. I only document my experience with BHB salts (and a non-commercial version at that), but say little to nothing about my experience with BHB esters or AcAc esters. But it will provide you will some context and understanding about what exogenous ketones are, and what they might do for athletic performance. We’ll likely podcast about the questions and topics above and cover other aspects of exogenous ketones in more detail.

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