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But sadly, whether due to government subsidy of high carb foods like corn and grain, funding from big companies like Gatorade and Powerbar, our sugar-addicted Western palates, or the constant (unfounded) fear mongering about saturated fats and heart disease, the type of research that shows these fat-burning and performance benefits of carbohydrate restriction simply get shoved under the rug.
The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used primarily to treat difficult-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fueling brain function. However, if little carbohydrate remains in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.[1] Around half of children and young people with epilepsy who have tried some form of this diet saw the number of seizures drop by at least half, and the effect persists even after discontinuing the diet.[2] Some evidence indicates that adults with epilepsy may benefit from the diet, and that a less strict regimen, such as a modified Atkins diet, is similarly effective.[1] Potential side effects may include constipation, high cholesterol, growth slowing, acidosis, and kidney stones.[3]
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?
Sensational article. I am experimenting with a low carb diet, high fats and moderate protein. I am not keeping strict notes on what I eat but I cut out almost all fruit and I eat eggs, spinach, kale, chard, avacados, hard cheese, walnuts (raw organic) and grass fed meet and butter. I take about 25-30ml of Brain Octane straight a day. I take your probiotic and colostrum (I need to get more regular) and I consume bone broth four days a week. I am looking to live longer and be healthier during that long life. In the short term I want to be smarter and be able to handle stress better. I would also love to avoid cancer and drop a deuce every day. My question is: Is there a point of carb consumption where even combining it with exogenous ketones using your recommendations it would be less effective or cause negative outcomes? Could one consume all the cards and sugar one wanted and use the supplements and still be getting into ketosis and reaping the benefits?

Moreover, recent studies show that the Inuit have evolved a number of rare genetic adaptations that make them especially well suited to eat large amounts of omega-3 fat.[57][58][59] And earlier studies showed that the Inuit have a very high frequency—68% to 81% in certain arctic coastal populations—of an extremely rare autosomal recessive mutation of the CPT1A gene—a key regulator of mitochondrial long-chain fatty-acid oxidation[60][61]—which results in a rare metabolic disorder known as carnitine palmitoyltransferase 1A (CPT1A) deficiency and promotes hypoketotic hypoglycemia—low levels of ketones and low blood sugar.[62] The condition presents symptoms of a fatty acid and ketogenesis disorder.[62] However, it appears highly beneficial to the Inuit[60] as it shunts free fatty acids away from liver cells to brown fat, for thermogenesis.[63][64] Thus the mutation may help the Inuit stay warm by preferentially burning fatty acids for heat in brown fat cells.[64] In addition to promoting low ketone levels, this disorder also typically results in hepatic encephalopathy (altered mental state due to improper liver function), enlarged liver and high infant mortality.[65] Inuit have been observed to have enlarged livers with an increased capacity for gluconeogenesis, and have greater capacity for excreting urea to remove ammonia, a toxic byproduct of protein breakdown.[57][66][67][68] Ethnographic texts have documented the Inuit's customary habit of snacking frequently [69] and this may well be a direct consequence of their high prevalence of the CPT1A mutation[70] as fasting, even for several hours, can be deleterious for individuals with that allele, particularly during strenuous exercise.[57][70] The high frequency of the CPT1A mutation in the Inuit therefore suggests that it is an important adaptation to their low carbohydrate diet and their extreme environment.[57][60][70]

While it is believed that carbohydrate intake after exercise is the most effective way of replacing depleted glycogen stores,[72][73] studies have shown that, after a period of 2–4 weeks of adaptation, physical endurance (as opposed to physical intensity) is unaffected by ketosis, as long as the diet contains high amounts of fat, relative to carbohydrates.[74] Some clinicians refer to this period of keto-adaptation as the "Schwatka imperative" after Frederick Schwatka, the explorer who first identified the transition period from glucose-adaptation to keto-adaptation.[75]

Under these circumstances, as soon as the body’s limited reserves of glucose starts to run out, your entire body switches its fuel supply to run almost completely on fat. The levels of the fat-storing hormone insulin levels become very low, and fat burning increases dramatically. You thus get easy access your fat stores, and can burn them off. This is great for losing excess weight. Studies prove that keto diets result in more weight loss, faster. There are also more potential benefits.
Putting — and then keeping — your body in ketosis isn’t exactly easy. You’ll need to severely minimize your intake of carbohydrates, eating no more than 20 to 50 grams (g) of carbs per day to get there and stay there. A single medium pear, for example, contains 26 g of carbs, and even foods that aren’t generally considered high in carbs — such as nuts and nonstarchy veggies — contain a small amount of carbohydrates, and so will need to be limited or avoided on this plan.

Kidney stones are a well-noted potential side effect of the ketogenic diet. Research published in the Journal of Child Neurology observed that among children following the keto diet as a treatment for epilepsy, 13 out of 195 subjects developed kidney stones. Children supplementing with potassium citrate in the study noticed a decreased likelihood of kidney stones. Speak with your healthcare practitioner about supplementing if kidney stones are a concern.

Some Inuit consume as much as 15–20% of their calories from carbohydrates, largely from the glycogen found in raw meats.[43][44][47][45][50] Furthermore, the blubber, organs, muscle and skin of the diving marine mammals that the Inuit eat have significant glycogen stores that are able to delay postmortem degradation, particularly in cold weather.[51][52][53][54][55][56]
Long-term disruption of menstruation can bring on serious side effects, including low bone density. “This is because estrogen is very important to bone health,” says Yawitz. “Studies have also found prolonged menstrual irregularity to increase risk for cardiovascular disease, depression, anxiety, and sexual dysfunction. It’s important to contact your ob-gyn if your cycles become irregular or if you stop having periods.”
Humans have always relied on ketones for energy when glucose sources were scarce (i.e. no fruits available during winter). It is a normal state of metabolism. In fact, most babies are born in a state of ketosis. However, with abundant sources of carbohydrate, people rarely access ketosis and it becomes a dormant metabolic pathway.Our ancestors likely had frequent periods of time when high carbohydrate food wasn’t immediately available. For this reason, our bodies are amazing at adapting to burning of ketones for fuel.

Fuels and feeds your brain: Ketones provide an immediate hit of energy for your brain, and up to 70% of your brain’s energy needs when you limit carbs.[6] Fat also feeds your brain and keeps it strong. Your brain is at least 60% fat, so it needs loads of good fats to keep it running.[7] Essential fatty acids such as omega-3s help grow and develop the brain, while saturated fat keeps myelin — the layer of insulation around the brain — strong so your neurons can communicate with each other.
Net carbs are what we track when following a ketogenic diet. This calculation is pretty straightforward. Net Carbs = Total Carbs – Fiber. For example, one cup of broccoli has 6g of total carbs and 2.4g of fiber. That would mean one cup of broccoli has 3.6g of net carbs. We count Net Carbs  because dietary fiber does not have a significant metabolic effect. 
Over 8–10 mmol/l: It’s normally impossible to get to this level just by eating a keto diet. It means that something is wrong. The most common cause by far is type 1 diabetes, with severe lack of insulin. Symptoms include feeling very sick with nausea, vomiting, abdominal pain and confusion. The possible end result, ketoacidosis, may be fatal and requires immediate medical care. Learn more
Keto breath, on the other hand, is less of a side-effect and more of a harmless inconvenience (your breath literally smells like nail polish remover). Basically, when your body breaks down all that extra fat on the keto diet, it produces ketones—one of which is the chemical acetone, Keatley previously told WomensHealthMag.com. (Yes, the same stuff that's in nail polish remover.)
It’s easy to get caught up on the “low-carb” part of the diet and not give enough attention to the “high-fat” part. Fat is what makes you full, gives you energy (when in ketosis), and makes food taste delicious. For most people this figure should be north of 70 percent of daily calories. Keep carbs under 20g, hit your protein goal, and eat fat until you’re full.

After about two to seven days of following the keto diet, you go into something called ketosis, or the state your body enters when it doesn't have enough carbs for your cells to use for energy. That's when you start making ketones, or organic compounds that your bod then uses in place of those missing carbs. At this point, your body also starts burning fat for more energy, says Beth Warren, R.D., founder of Beth Warren Nutrition and author of Living A Real Life With Real Food.
“For events longer than 60 minutes, consuming 0.7 g carbohydrates·kg-1 body weight·h-1 (approximately 30-60 g·h-1) has been shown unequivocally to extend endurance performance. Consuming carbohydrates during exercise is even more important in situations when athletes have not carbohydrate-loaded, not consumed pre-exercise meals, or restricted energy intake for weight loss. Carbohydrate intake should begin shortly after the onset of activity; [and continue] at 15- to 20-min intervals throughout the activity.”

Therefore, more people experiencing "keto crotch" need to visit doctors to determine what's really happening. It could be that some of the people claiming "keto crotch" are instead detecting smells that are not related to their diets. Many different smells could emanate from your crotch, some are normal, some are not. Conversely, who knows for sure what a drastic change in your diet may do to different parts of your body? There is still a lot unknown about the links between nutrition and your various bodily functions. You are a complex system with many unknowns. The keto crotch could be a real phenomenon, but more scientific evidence and studies are needed.
If you have a functioning pancreas that can produce insulin – i.e. you don’t have type 1 diabetes – it would be extremely hard or, most likely, impossible to get ketoacidosis even if you tried. That’s because high ketone levels result in release of insulin, that shuts down further ketone production. In other words, the body has a safety net that normally makes it impossible for healthy people to get ketoacidosis.
These affect your brain and spine, as well as the nerves that link them together. Epilepsy is one, but others may be helped by a ketogenic diet as well, including Alzheimer’s disease, Parkinson’s disease, and sleep disorders. Scientists aren’t sure why, but it may be that the ketones your body makes when it breaks down fat for energy help protect your brain cells from damage.

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A survey in 2005 of 88 paediatric neurologists in the US found that 36% regularly prescribed the diet after three or more drugs had failed, 24% occasionally prescribed the diet as a last resort, 24% had only prescribed the diet in a few rare cases, and 16% had never prescribed the diet. Several possible explanations exist for this gap between evidence and clinical practice.[34] One major factor may be the lack of adequately trained dietitians, who are needed to administer a ketogenic diet programme.[31]
Long-term use of the ketogenic diet in children increases the risk of slowed or stunted growth, bone fractures, and kidney stones.[18] The diet reduces levels of insulin-like growth factor 1, which is important for childhood growth. Like many anticonvulsant drugs, the ketogenic diet has an adverse effect on bone health. Many factors may be involved such as acidosis and suppressed growth hormone.[38] About one in 20 children on the ketogenic diet develop kidney stones (compared with one in several thousand for the general population). A class of anticonvulsants known as carbonic anhydrase inhibitors (topiramate, zonisamide) are known to increase the risk of kidney stones, but the combination of these anticonvulsants and the ketogenic diet does not appear to elevate the risk above that of the diet alone.[39] The stones are treatable and do not justify discontinuation of the diet.[39] Johns Hopkins Hospital now gives oral potassium citrate supplements to all ketogenic diet patients, resulting in one-seventh of the incidence of kidney stones.[40] However, this empiric usage has not been tested in a prospective controlled trial.[9] Kidney stone formation (nephrolithiasis) is associated with the diet for four reasons:[39]
The ketogenic diet is calculated by a dietitian for each child. Age, weight, activity levels, culture, and food preferences all affect the meal plan. First, the energy requirements are set at 80–90% of the recommended daily amounts (RDA) for the child's age (the high-fat diet requires less energy to process than a typical high-carbohydrate diet). Highly active children or those with muscle spasticity require more food energy than this; immobile children require less. The ketogenic ratio of the diet compares the weight of fat to the combined weight of carbohydrate and protein. This is typically 4:1, but children who are younger than 18 months, older than 12 years, or who are obese may be started on a 3:1 ratio. Fat is energy-rich, with 9 kcal/g (38 kJ/g) compared to 4 kcal/g (17 kJ/g) for carbohydrate or protein, so portions on the ketogenic diet are smaller than normal. The quantity of fat in the diet can be calculated from the overall energy requirements and the chosen ketogenic ratio. Next, the protein levels are set to allow for growth and body maintenance, and are around 1 g protein for each kg of body weight. Lastly, the amount of carbohydrate is set according to what allowance is left while maintaining the chosen ratio. Any carbohydrate in medications or supplements must be subtracted from this allowance. The total daily amount of fat, protein, and carbohydrate is then evenly divided across the meals.[37]
There’s also some evidence that it might help with type 2 diabetes. “An emerging body of research is finding that a keto plan may have some real benefits thanks to its ability to improve the body’s ability to use insulin and also help control appetite, which can result in easier weight loss,” says Karen Ansel, R.D.N., co-author of Healthy in a Hurry.
^ Ringberg TM, White RG, Holleman DF, Luick JR (1981). "Body growth and carcass composition of lean reindeer (Rangifer tarandus tarandusL.) from birth to sexual maturity" (PDF). Canadian Journal of Zoology. 59 (6): 1040–1044. doi:10.1139/z81-145. ISSN 0008-4301. Body growth and carcass composition were measured in lean reindeer during the juvenile growth period between birth and 3 years of age. Mean carcass weight in these lean reindeer was 56 ± 4% of body weight and the deposition of body muscle and bone mass was linearly correlated with body weight after the 1st month of age. The weight of the brain relative to body weight and carcass weight declined, while the relative changes in heart, liver, kidneys, parotid glands, and tissues of the gastrointestinal tract were small after the neonatal period. The extractable fat content in carcasses increased from 4.4 to 11.4% of wet weight or approximately 100 g fat at birth and 3.5 kg fat in adult reindeer. Fat-free dry matter represented a constant percentage (18–20%) of wet carcass weight independent of body weight after the neonatal period, while a significant inverse relationship between carcass fat and body water was found.
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.
The remaining calories in the keto diet come from protein — about 1 gram (g) per kilogram of body weight, so a 140-pound woman would need about 64 g of protein total. As for carbs: “Every body is different, but most people maintain ketosis with between 20 and 50 g of net carbs per day,” says Mattinson. Total carbohydrates minus fiber equals net carbs, she explains.
Although many hypotheses have been put forward to explain how the ketogenic diet works, it remains a mystery. Disproven hypotheses include systemic acidosis (high levels of acid in the blood), electrolyte changes and hypoglycaemia (low blood glucose).[19] Although many biochemical changes are known to occur in the brain of a patient on the ketogenic diet, it is not known which of these has an anticonvulsant effect. The lack of understanding in this area is similar to the situation with many anticonvulsant drugs.[56]
In the US especially, coconut oil and MCT oil manufacturers are legally allowed to claim that lauric acid is an MCT because chemists named it that way, even though it does not act like other true biological MCT oils. If you are relying on plain coconut oil or “MCT-labeled” oil to get enough useful MCTs, think again and check the label: odds are you’re getting very few of the potent, ketogenic shorter chain MCTs (also known as “C8” and “C10”), and instead getting mostly cheaper but ineffective lauric acid.
Hi Ben…first, I have learned so much from you, thank you! I’m interested in using exogenous ketone supplements and I have a question for you. I just read the transcript of an interview Dave Asprey did with Dr. Richard Veech (episode 299). He advises against them, and says they can even be harmful. I was disappointed to read this, and wanted to ask you about it, since I respect your opinion greatly….thank you.
I am curious if someone takes any or too much MCT oil (5-10 tablespoons/day) or Exogenous Ketones will the liver slow/stall or shut off endogenous ketone production as you are providing the ketones exogenously and thereby you may NEED to supplement ketones to maintain ketone levels or you may suffer a short term ketone deficit while the liver adjusts to making them on its own again. A parallel I am thinking of is exogenous testosterone supplementation and the hypothalamus/endocrine system slowing/stopping endogenous testosterone production (seen in bodybuilders).