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.

I (Kim) researched the topic and planned and ran the experiment under the guidance and supervision of Dr. Andreas Eenfeldt, who touched base with me every step of the way to check the experiment design and execution for scientific rigor (to the greatest degree possible) and who has edited this writeup for quality and trustworthiness reasons. I also consulted with other keto experts and researchers to gather feedback both on the experiment design and the results data. They are referenced in the text when this was the case.
If you read about ketosis in magazine or heard about it in a podcast and wanted to jump on the bandwagon, then I think you should avoid it. Remember, it is a strict diet, and the potential health downsides may not be worth the upsides, unless you are working with a medical professional and or you are tracking your labs to see what’s going on with your health (thyroid).
The famous keto-breath is powerful enough to throw shade on your increasingly ripped rig. The mouth-based ketones are released when your body scalds fat are responsible for the pong. Going into ketosis by changing your diet means your body doesn’t have carbs as a fuel source, so you’re using fats and proteins for energy, which fuels the potency of the fireworks seeping from your grill. The same can happen when taking supplements, but not by the same degree – proving that changing your diet it obviously a more potent fat burning tool. A lot of people also report gastric distress, so you could offend those you’re co-habituating with. What’s more, they can have a slight diuretic effect, which can deplete your magnesium, potassium and sodium stores, so make sure your levels are topped up when you’re out for a extra long exercise stint. Research in Nutrition and Metabolism on animals, found there were no negative side effects, but whether this extends to humans is still up for discussion. Fortunately, you’re more likely benefit from the upsides such as improved endurance, appetite suppression and fat burning.

The keto-esters are more appropriate for delivering higher doses of BOHB, but with repeated dosing can push the limits of taste and GI tolerance. There has been fairly extensive research on a compound 3-hydroxybutyl 3-hydroxybutyrate that is converted via hydrolysis and liver metabolism to yield 2 molecules of ketones, presumably mostly D-BOHB (Clarke 2012 and 2014). In a study involving lean athletes, an approximate 50 gram dose raised blood BOHB levels to 3 mM after 10 min and reached 6 mM by 20 min. Submaximal exercise resulted in increased ketone disposal from 2 to 3 hours and contributed significantly to whole body energy use during exercise (Cox 2016). This product has been shown to significantly reduce appetite after a single dose (Stubbs 2018) but its effect on body weight in humans over a longer period of time has not been studied, nor has its effect on blood glucose control been reported in humans with type 2 diabetes. However a single dose prior to a glucose tolerance test in healthy humans reduced blood glucose area-under-curve by 11% and non-esterified fatty acid area-under-curve by 44% (Myette-Cote 2018).
Another source of the D-BOHB isomer is an evolutionarily ancient energy source for micro-organisms. Poly-BOHB is a long chain of D-BOHB molecules strung end-to-end. It functions in many single-cell organisms as a concentrated energy source similar to glycogen in mammals, but whereas glycogen breakdown releases individual glucose molecules, poly-BOHB hydrolysis releases single D-BOHB molecules.

Skipping breakfast on a keto diet is a popular way to boost ketone levels. Despite the age-old myth that breakfast is the most important meal of the day, research shows that breakfast skipping is not only safe but beneficial. Skipping breakfast causes intermittent ketosis and also suppresses appetite [6]. Make sure your next meal of the day isn't too late in the evening as studies show that eating meals late at night causes weight gain and impairs fat metabolism [7].
With single doses of the D-BHB ester as a sports drink, gastrointestinal (GI) side effects are rare. Some studies have reported mild GI side-effects of HVMN Ketone drinks at extremely high doses (4x serving size) or when given in a thick, meal replacement formulation.10,13 However, other studies of athletes reported there were no side-effects of ketone ester drinks hindering sport performance.11,14
But going keto takes work. You have to overhaul your diet, restrict certain classes of foods, and pay close attention to what you eat. People prefer to avoid work if they can. They like shortcuts. Exogenous ketone supplements promise a shortcut—swallow this pill or mix this powder into your water and see your ketones skyrocket without changing the rest of your diet.
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.
Also, it’s important to remember that just because something may be SAFE (and to reiterate, I’m not saying a long term ketogenic diet is safe), it doesn’t mean it’s good for you or beneficial. Running Marathons could be considered safe (especially if it’s on a closed race circuit), but does this mean it’s good for you? Or should you be out running marathons every day?
That’s not all. Though Prüvit in particular has a legion of fans (the brand has nearly 35,000 Instagram followers and some 256,000 likes on Facebook) and a small team of affiliated medical experts, there’s no hard science on Prüvit or similar products. (Prevention reached out to several Prüvit experts and employees for interviews but did not receive a response.) The research page on the brand’s website does include links to legit scientific studies. But the studies are on the keto diet—not on Prüvit’s products. When it comes to research on the actual supplements, the brand’s website simply says “Human studies on finished products (underway) at various universities and research facilities.” In other words, there’s no scientific evidence available yet to show that they actually work.
I heard a rep from Perfect Keto on a podcast and your Exogenous Ketones. I ordered and received it the other day. I see from this article that I should not do a full scoop at once, but break it up in a day. Good to know. I had about a half scoop before I worked out this morning and could tell I had more energy. Loved that. Just curious….any ideas how long it will take me to get back into ketosis and fat burning?? (I know it depends on what I eat, but a general idea that I promise not to hold you too! (I’m actually missing having ‘keto breath!)
Exercise or performing an extensive workout during the day is a perfect way to burn all those glycogen reserves in your body. Performing a HIIT or High Intensity Interval Training is a perfect type of exercise to do this. So, the next morning when you are awake, get set on an intense exercise session (remember, in the morning, not the afternoon). This will keep the cortisol level lowered during the evening when you wish to have some rest.
When you restrict carbs, the kidneys excrete a lot of sodium. Not replacing this sodium can leave you feeling light headed. I recommend having a big glass of spring water with ½ teaspoon of Celtic sea salt twice a day (first thing in the morning and midafternoon are two times that work well). A long with this, make sure you use a lot of salt on your meals.

MCT Oil is a keto supplement that helps your body make ketones. The oil contains pure medium-chain triglycerides (MCTs), which are types of fatty acids that your body prefers using for immediate energy. Unlike long-chain fatty acids, MCTs don't require enzymes and bile for digestion and they go straight to the liver where they are used for making free fatty acids or ketones. Studies on MCTs show that they promote weight loss [5].

Intermittent fasting will significantly help the body transition into ketosis as limiting your consumption of food for that many hours will help deplete the system of any excess glucose. It’s a shock to the system and research has shown that daily fasting can have other profound effects aside from weight control such as autophagy, lowering risks of heart disease and diabetes, as well as an improvement in cognitive function. So if you’re still wondering how to get into ketosis in 24 hours, then fasting will surely kick things into gear!
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.
Background and aims: Currently there is considerable interest in ketone metabolism owing to recently reported benefits of ketosis for human health. Traditionally, ketosis has been achieved by following a high-fat, low-carbohydrate “ketogenic” diet, but adherence to such diets can be difficult. An alternative way to increase blood D-β-hydroxybutyrate (D-βHB) concentrations is ketone drinks, but the metabolic effects of exogenous ketones are relatively unknown. Here, healthy human volunteers took part in three randomized metabolic studies of drinks containing a ketone ester (KE); (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, or ketone salts (KS); sodium plus potassium βHB.

Exercise or performing an extensive workout during the day is a perfect way to burn all those glycogen reserves in your body. Performing a HIIT or High Intensity Interval Training is a perfect type of exercise to do this. So, the next morning when you are awake, get set on an intense exercise session (remember, in the morning, not the afternoon). This will keep the cortisol level lowered during the evening when you wish to have some rest.

Fortunately a new way to test ketosis has been developed - and that is by measuring acetone levels in the breath. This is rather new technology but based on the reports I have seen it does look reasonably reliable. The testing process is simple, you use a device like that made by Ketonix, you breathe into it, wait a minute or so and it will give you a color indicating the state of ketosis you are in. However, there are numerous downsides:
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.
88. Yost T, Erskine J, Gregg T, Podlecki D, Brass E, Eckel R. Dietary substitution of medium chain triglycerides in subjects with non-insulin-dependent diabetes mellitus in an ambulatory setting: impact on glycemic control and insulin-mediated glucose metabolism. J Am Coll Nutr. 1994;13(6):615–22. doi: 10.1080/07315724.1994.10718457. [PubMed] [CrossRef]
Calories do matter, even on a ketogenic diet. If you consume more calories than your body uses, you’re going to gain weight. Period. What you mean to say is that it’s very difficult to eat your entire day’s worth of calories on a ketogenic diet because fats are so satiating. This distinction is important to keep in mind for those who generally have a voracious appetite (like me).

Increased levels of BHB in the body were found to be associated with greater cognitive performance through better performance in memory recall tests12 on a study of 20 subjects with Alzheimer’s disease or demonstration of a mild cognitive deficit. Similarly, BHB ketone esters helped to reverse symptoms of Alzheimer's Disease in one clinical case study.13 More research in humans is needed, but the various hypotheses are backed up by strong animal data.

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Medical Disclaimer: The material on this site is provided for informational purposes only and is not medical advice. Always consult your physician before beginning any diet or exercise program.

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