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In addition, most studies that compare carbohydrate utilization with fat utilization fail to take into account the fact that full “fat adaptation” that allows you to gain all the benefits of using fat as a fuel actually takes time – often more than four weeks – and up to a couple years. But since most studies that compare fat and carbohydrate burning are short-term, you rarely see the benefits of this kind of fat adaptation actually fleshed out in research. Instead, the average research participant begins the study in a non-fat adapted state, gets either a high fat or high carb diet, then launches into exercise. But in an ideal study, that person would have followed either a high-fat or high-carb diet for many months before getting their fat burning capability investigated.

Physical or mental fatigue during workouts (or while you’re sitting at your office) is caused by the low blood glucose that occurs as your carbohydrate fuel tank approaches empty (also known as the infamous “bonk”, which is awesomely demonstrated in this funniest running cartoon I’ve ever seen). Because it is generally (and sadly) accepted as orthodox knowledge that the human body can’t burn fat as a reliable fuel source – especially when you’re exercising for long periods of time or at high intensities – nearly every shred of nutrition science is simply looking for ways to somehow increase the size of your carbohydrate fuel tank and hack the body to allow it to store more carbs or absorb carbs more quickly.


If you are already in ketosis and accustomed to high-fat, low-carb diets, you can take one heaping scoop in about eight ounces of water fifteen minutes prior to working out. It stays in your system and will provide your body with elevated ketone levels for about three hours. When taken as a pre-workout, KetoCaNa has also been shown to decrease the amount of oxygen consumed at a given power output.
Hi Ben – Great article. I had trouble at the end figuring out if you were now eating high fat (60-80% of calories), or if you went back to something closer to 50% fat calories and higher carbs and are using exogenous ketones to get int ketosis when needed. Are you doing any carbs at night or a refeed, or just having higher carbs on most days? Thanks
Wow! Amazing article. I don’t read blogs regularly, but I’ll be reading more of yours. I am on day 11 of a fast to get me into ketosis; 7 days bone broth and now on day-4 water only. Intentions are weight loss (10# down, 15# more to go) and immunity improvement/gut help. Planning 9 days of whey water, fermented veggies and mad probiotics when the water days are done (day 14?). After this fast I want to stay fat adapted, start training again and get down to 8% body fat. I believe you have cut that journey significantly with this article. Thank you.
3 years ago I was 500 pounds at my absolute worst. Went through a traumatic experience when I was 17 and afterwards the weight just seemed to add on over the years. I'd always been a big guy but it got really bad. Decided to start the keto diet after looking into healthier lifestyles and fast forward two years later (with intermittent fasting and gym training) I had lost 260 pounds. I kept under 1200 calories a day and the best feeling was not constantly being hungry. The last year has been more of a maintenance but with keto cycling.

Those issues can be part of what's known as the “keto flu,” Warren says. Other side effects of the keto diet, all of which are tied to carb withdrawal, can include lightheadedness, nausea, mental fog, cramps, and headaches, in addition to tiredness. Luckily, the keto flu doesn't usually last more than a week—which is coincidentally about when people start to see the number on the scale go down, says Warren.

I see a lot of people say that ketosis is great for insulin sensitivity. BUT, in my experience ketosis causes physiological insulin resistance whereby the muscles and liver are sparing glucose for the brain. Hence, glucose tolerance actually goes down during ketosis. As such, is it possible that post workout carbs could do a lot more damage than they would on a non-ketogenic diet? Or maybe, as Kiefer suggests, glucose uptake post workout is not moderated by insulin at all i.e. muscles soak up glucose regardless of their insulin sensitivity? Or maybe cyclical ketosis doesn’t allow liver glycogen to get low enough to trigger physiological insulin resistance?
The same goes for people with type 2 diabetes. While some preliminary research suggests the keto diet may be safe and effective for certain people with type 2 diabetes, there’s still the risk for low blood sugar, especially for those on insulin, and the keto diet omits certain food groups known to benefit those with this disease. For example, a study published in September 2016 in the journal Nutrients highlights the importance of whole grains for helping to control weight as well as episodes of high blood sugar. Whole grains are off-limits on the ketogenic diet.
“Certainly, the quality of fat counts,” says Yawitz. “There’s a big difference nutritionally between bacon and almonds. As much as possible, people set on the keto diet should emphasize plant-based, unsaturated fats like nuts, seeds, olive oil, and avocado, which have even been shown to protect the heart.” If you have high cholesterol or other risk factors for heart disease, you should speak with your doctor before beginning the keto diet. This is because the diet may — but doesn't have to — include large amounts of saturated fat. Some studies have shown increases in cholesterol and triglycerides in people following the diet, while other research reveals that the keto diet may actually decrease heart disease risk as well as saturated fat intake.
Hello, may I ask if someone has some experience week fasting for 14 days? I was told that the food which should be started taken after 14 days of fasting has to be in very simple and in slow amount. Unfortunately 1-2 days after fasting I am allowed to take only bouillon out of buckwheat, barley, from the 3rd day buckwheat mush, and only from 5th day milk or sour cream, oil since 11th day. Can anyone advice how should I adopt this come back food path to Ketogenic diet? Thank you in advance, Maria

A systematic review in 2018 looked at 16 studies on the ketogenic diet in adults. It concluded that the treatment was becoming more popular for that group of patients, that the efficacy in adults was similar to children, the side effects relatively mild. However, many patients gave up with the diet, for various reasons, and the quality of evidence inferior to studies on children. Health issues include high levels of low-density lipoprotein, high total cholesterol, and weight loss.[24]
Here are a few of the most common side effects that I come across when people first start keto. Frequently the issues relate to dehydration or lack of micronutrients (vitamins) in the body. Make sure that you’re drinking enough water (close to a gallon a day) and eating foods with good sources of micronutrients. To read more on micronutrients, click here >

Once inside the mitochondrion, the dominant way that the bound fatty acids are used as fuel in cells is through β-oxidation, which cleaves two carbons off of the acyl-CoA molecule in every cycle to form acetyl-CoA.[24] Acetyl-CoA enters the citric acid cycle, where it undergoes an aldol condensation with oxaloacetate to form citric acid; citric acid then enters the tricarboxylic acid cycle (TCA), which harvests a very high energy yield per carbon in the original fatty acid.[25][26]

On a low carb or ketogenic diet my fasting blood sugar is 90-120. I think it may get higher the lower carb I go. Most internet sources say don’t worry about it, worry about your Ha1c. Is this insulin resistance? Anyone have better information? If I do a water fast my morning blood sugar will go down and down each day, til it reaches about 50 in 4 days. But as soon as I start eating it pops right back up.
Urine test for diabetes: What you need to know Urine tests for diabetes check for protein, ketones, and glucose. They are frequently used for diagnosing and monitoring diabetes, and to assess people who are experiencing symptoms, such as fatigue or nausea. Depending on the results, recommendations may be given about medication or lifestyle changes that could help. Read now
You need to do a “common man’s” version of a good ketogenic nutrition program or discussion. Great article, and I leaned a few things. Those Ketone Salts and other supplements can get pricey. I eat a very low carb and high fat diet and meander in and out of ketosis during the week. A pure ketogenic diet is so restrictive that meals it can get very repetitive during the week. I’d like to learn more about cooking with oils and how temperature effects their qualities. I can only handle eating so much raw food, and I love to cook my greens and other vegetables in bacon fat and coconut oil. It will be next May before I can get my blood work performed (insurance reasons) so until then I’ll need to be careful and hold back on those after supper dark chocolate excursions! Thanks!!
Bulk buy and cook. If you’re someone who doesn’t like to spend a lot of time in the kitchen, this is the best of both worlds. Buying your food at bulk (specifically from wholesalers) can reduce the cost per pound tremendously. Plus, you can make ahead food (bulk cook chicken thighs for pre-made meat, or cook entire meals) that are used as leftovers, so you spend less time cooking.
Ketosis is a metabolic state where most of the body's energy supply comes from ketone bodies in the blood, in contrast to a state of glycolysis where blood glucose provides most of the energy. Ketosis is characterized by serum blood concentrations of ketone bodies over 0.5 millimolar with low and stable levels of insulin and blood glucose. However, with ketone supplementation (as you’ll learn about later in this article) ketosis can actually be induced even when there are high levels of blood glucose.

I will begin a medically supervised weight loss program on Tuesday, that is intended to put me into ketosis via a very low calorie, high protein diet of shakes for two meals per day and one (controlled) regular meal. The overview of the program says to expect up to 2 weeks of foggyness and crankiness while getting in to ketosis. Will taking KetoCaNa 3 times a day for two days in advance of starting the diet (and during the introduction to the diet) help move me more quickly through the foggy, cranky phase? And should I also be eating (a ketogenic diet) during those two days or only drinking the KetoCaNa? My thanks in advance for any light you can shed on this!
Ketones are a special type of fat that can stimulate the pathways that enhance the growth of new neural networks in the brain. A ketogenic diet is one that is high in fats, and this diet has been a tool of researchers for years, used notably in a 2005 study on Parkinson’s patients finding an improvement in symptoms after just 28 days. The improvements were on par with those made possible via medication and brain surgery. Other research has shown the ketogenic diet to be remarkably effective in treating some forms of epilepsy, and even brain tumors.

Ben – curious about your thoughts on this. I went into ketosis (using LOTS of coconut oil) but it raised my cholesterol and doc was worried about my lp(a) level (17mg/dL on VAP) even though crp was 0.5, trigs 51 and a1c was 5.2. Advised a low fat diet. Have you seen this before with folks on a lchf/ketosis diet and is there anything to be concerned about? Off to read your coconut oil article. Thank you!
After 2 years in ketosis suddenly I find my blood glucose has risen to high levels even while in ketosis. I thought it was the dawn phenomenon, stress hormones like cortisol but now I am beginning to think I am eating too many exongenous keytones like too much MCT oil? I am not taking exogenous keytone supplements but wondering if too much oil/ fat in the diet generates exogenous keytones which inhibits the livers production of endogenous keytones. I have read if the liver is producing endogenous keytones it is not at the same time producing glucose through gluconeogenisis?

Acetone, the least abundant ketone, is present in the breath and is responsible for the unpleasant odor. Acetone is a solvent in nail polish, if that gives you an idea of what it might smell like. But it's not as bas as it sounds; acetone breath is a sign of ketosis and fat burning. It's the ketone measured in breath tests used for detecting ketosis.6


After that happened, I set out once again to find some kind of carbohydrate source that allows one to maintain elevated liver glycogen and muscle glycogen stores without getting all the blood-sugar level roller coaster rides or gut rot and fermentation that many typical sports nutrition carbohydrate sources such as fructose and maltodextrin can cause.
Twenty elite ultra-marathoners and ironman distance triathletes performed a maximal graded exercise test and a 180 min submaximal run at 64% VO2max on a treadmill to determine metabolic responses. One group habitually consumed a traditional high-carbohydrate (HC: n = 10, %carbohydrate:protein:fat = 59:14:25) diet, and the other a low-carbohydrate (LC; n = 10, 10:19:70) diet for an average of 20 months (range 9 to 36 months).
Ketone bodies are acidic, but acid-base homeostasis in the blood is normally maintained through bicarbonate buffering, respiratory compensation to vary the amount of CO2 in the bloodstream, hydrogen ion absorption by tissue proteins and bone, and renal compensation through increased excretion of dihydrogen phosphate and ammonium ions.[9] Prolonged excess of ketone bodies can overwhelm normal compensatory mechanisms, defined as acidosis if blood pH falls below 7.35.

I’m not sure if I really understand the idea of exogenous Ketones putting ones body into a state of KETOSIS, in that their own fat cells will be burned for fuel. Won’t the body just use the exogenous ketones and energy and continue to use glucose sources as well? How does taking ketones, make the body burn it’s own fat stores? I always thought that one would have to be in a state of energy deprivation for the body to actually begin to use the TG in the fat cells to generate ATP. Please let me know what I’m missing…

The Johns Hopkins Hospital protocol for initiating the ketogenic diet has been widely adopted.[43] It involves a consultation with the patient and their caregivers and, later, a short hospital admission.[19] Because of the risk of complications during ketogenic diet initiation, most centres begin the diet under close medical supervision in the hospital.[9]
Great article! As someone who just started a “ketogenic diet” two weeks ago, I am opting to hold off on using ketone supplements for the following reason. You state how “Keto-adaptation occurs when you have shifted your metabolism to relying on fat-based sources, instead of glucose (sugar) sources, as your primary source of fuel.” If the goal is to “switch” our body’s energy supply to ketones and one uses supplemental ketones, how do they really ever know if their body has successfully accomplished this goal if they are using supplemental ketones? Aren’t they getting a false sense of ketosis if their blood or breath tests show them above 0.5 millimolar through the use of the supplements? I understand that it may take me longer to reach ketosis naturally but I guess I see it was worth it to truly reap all of the benefits that you outline in your article.
-Cancer: Numerous studies have found that the risk for cancer increases with high blood sugar, which makes sense, since cancer cells feed primarily on glucose. This includes cancers of the endometrium, pancreas, and colon and colorectal tumors. Tim Ferriss recently hosted a fantastic article by Peter Attia about this very issue, and how ketosis may indeed be a potential cancer cure.
It is possible to combine the results of several small studies to produce evidence that is stronger than that available from each study alone—a statistical method known as meta-analysis. One of four such analyses, conducted in 2006, looked at 19 studies on a total of 1,084 patients.[23] It concluded that a third achieved an excellent reduction in seizure frequency and half the patients achieved a good reduction.[18]
2) I'm currently using Ketocana and in that section you state "Similar to the BHB salts and MCT’s from the KETO//OS I discuss above, powdered forms of ketones are excellent if you don’t want to completely eliminate carbohydrates or fat or eat copious amounts of fats, but want to simultaneously maintain high levels of blood ketones." – How would eating copious amounts of fat be a negative? Wouldn't that help contribute to a ketogenic state?

Short-term results for the LGIT indicate that at one month approximately half of the patients experience a greater than 50% reduction in seizure frequency, with overall figures approaching that of the ketogenic diet. The data (coming from one centre's experience with 76 children up to the year 2009) also indicate fewer side effects than the ketogenic diet and that it is better tolerated, with more palatable meals.[18][50]
In dairy cattle, ketosis is a common ailment that usually occurs during the first weeks after giving birth to a calf. Ketosis is in these cases sometimes referred to as acetonemia. A study from 2011 revealed that whether ketosis is developed or not depends on the lipids a cow uses to create butterfat. Animals prone to ketosis mobilize fatty acids from adipose tissue, while robust animals create fatty acids from blood phosphatidylcholine (lecithin). Healthy animals can be recognized by high levels of milk glycerophosphocholine and low levels of milk phosphocholine.[76] Point of care diagnostic tests are available and are reasonably useful.[77]
Cyclical keto diet: The Bulletproof Diet falls into this category. You eat high fat, low carb (less than 50 grams of net carbs a day) five to six days of the week. On day seven, you up your carb intake to roughly 150 grams, during what’s called a carb refeed day. Carb cycling this way helps you avoid the negative effects some people experience when they restrict carbs long term, like thyroid issues, fatigue and dry eyes.[9][10]  Learn more here about how carb cycling works.
Shifting your metabolism and achieving ketosis may speed up weight loss and result in other health benefits, like more energy and a lower blood pressure. But while ketosis is a preferred nutritional state for some people, it isn’t recommended for everyone — and it’s not a good long-term eating approach due to its restrictive nature, which may lead to potentially dangerous nutritional deficiencies.
When you’re eating the foods that get you there (more on that in a minute), your body can enter a state of ketosis in one to three days, she adds. During the diet, the majority of calories you consume come from fat, with a little protein and very little carbohydrates. Ketosis also happens if you eat a very low-calorie diet — think doctor-supervised, only when medically recommended diets of 600 to 800 total calories.
To understand exogenous ketones, you should know that there are three types of ketones: beta-hydroxybutyrate (BHB), acetoacetate (ACA) and acetone, and all three are the normal by-products of fat breakdown by your body. In much the same way as glucose, ketones can be used by your tissues, especially your brain, diaphragm and heart and are actually a far more efficient fuel source than glucose.
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