Alison Moodie is a health reporter based in Los Angeles. She has written for numerous outlets including Newsweek, Agence France-Presse, The Daily Mail and HuffPost. For years she covered sustainable business for The Guardian. She holds a master’s degree from Columbia University’s Graduate School of Journalism, where she majored in TV news. When she's not working she's doting on her two kids and whipping up Bulletproof-inspired dishes in her kitchen.
The ketogenic diet is usually initiated in combination with the patient's existing anticonvulsant regimen, though patients may be weaned off anticonvulsants if the diet is successful. Some evidence of synergistic benefits is seen when the diet is combined with the vagus nerve stimulator or with the drug zonisamide, and that the diet may be less successful in children receiving phenobarbital.[18]
So which MCT to pick? Brain Octane (pure C8) provides the fastest rise in ketones and burns the cleanest, with minimal gut irritation. XCT oil is more affordable but works more slowly with less direct cognitive effects. The capric acid C10 in XCT Oil doesn’t break down into ketones as quickly as pure caprylic C8, but capric acid C10 is more affordable, so you can save money by going with the XCT oil. XCT oil still goes to brain energy, just not as quickly as Brain Octane. Both can be used for energy without processing by the liver, unlike many other fats and oils.

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]

Acetyl-CoA can be metabolized through the TCA in any cell, but it can also undergo a different process in liver cells: ketogenesis, which produces ketone bodies.[27] Ketone bodies are also produced in mitochondria, and usually occur in response to low blood glucose levels.[28] When glucose levels are low, oxaloacetate is diverted away from the TCA cycle and is instead used to produce glucose de novo (gluconeogenesis). But when oxaloacetate is unavailable to condense with acetyl-CoA, acetyl-CoA cannot enter the cycle, and so the body has evolved an alternative way to harvest energy from it.
^ 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.

The longer cholesterol circulates in your bloodstream, the higher the likelihood that it will dig its way into an endothelial wall and potentially contribute to atherosclerosis or plaque formation. This is why it’s so dangerous to eat a high-fat diet, but to also have your nightly dark chocolate bar, overdo it on the red wine, or have weekly “cheat days” with pizza, pasta, or sugar-laden ice cream.
“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.

Awesome info. I’ve been LCHF moderate protein (about 1 g per lean lbs/mass) and 50-100g of carbs for about a year. I’d consume around 2500 cals. I’m active 4-5 days a week (60-90 min cycling sessions) I started using MCT/Butter coffee. It surpressd my appetite and I would only eat whole food at lunch/dinner…still LCHF, but since my appetite was lower I was only takin in about 1800 cals. After about 2 weeks I started to gain body fat. Do you think the reduced caloric intake is the culprit? Should I “force” myself to eat…maybe up the MCT intake to make up the difference?
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A Cochrane systematic review in 2018 found and analysed eleven randomized controlled trials of ketogenic diet in people with epilepsy for whom drugs failed to control their seizures.[2] Six of the trials compared a group assigned to a ketogenic diet with a group not assigned to one. The other trials compared types of diets or ways of introducing them to make them more tolerable.[2] In the largest trial of the ketogenic diet with a non-diet control[16], nearly 38% of the children and young people had half or fewer seizures with the diet compared 6% with the group not assigned to the diet. Two large trials of the Modified Atkins Diet compared to a non-diet control had similar results, with over 50% of children having half or fewer seizures with the diet compared to around 10% in the control group.[2]
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.

As I learned in a University of Connecticut lab experiment I mentioned earlier in this article (gory details here), a high-fat, low-carb diet can teach and allow the muscles to tap into more fat for fuel, making your body crave less use of oxygen in the large muscles of the legs, arms or other areas that you’ve learned oxygen gets shunted away from when deep underwater.


There are many misconceptions about ketosis. The most common is mixing it up with ketoacidosis – a rare and dangerous medical condition that mostly happen to people with type 1 diabetes if they don’t take insulin. Even some health care professionals tend to mix up these two situations somewhat, perhaps due to the similar names and a lack of knowledge about the distinct differences.
Because some fruits have more carbs than others, knowing which to avoid is key for accelerating weight loss and reaping other possible benefits of keto. Just know that large, long-term, randomized controlled trials on the keto diet are limited, so it’s unclear whether keto is safe and effective to follow for the long haul, according to Harvard Medical School.
So if your high-fat diet includes a high amount of roasted seeds or roasted nuts, nut butters, heated oils such as heated coconut oil or heated extra virgin olive oil, barbecued meats or meats cooked at very high temperatures, then your triglyceride count is going to go up. You should have triglycerides that are less than 150mg/dL, and a triglyceride to HDL ratio that is no more than 4:1, and in most of the healthiest people I’ve worked with, triglycerides are under 100 and the triglyceride to HDL ratio is less than 2:1. If your ratio is whacked, your ketotic diet isn’t doing you any favors.

A lot of changes are happening in your body and you’re going to feel it! The first five to seven days can be pretty rough, but your body is getting over its dependency on sugar. During this time of transition it is essential that you supplement electrolytes. Your body is flushing out lots of water, and with that goes electrolytes. The Keto Flu can be greatly reduced if you add sodium, potassium and magnesium to your diet. Check out our supplements page for a list of electrolyte supplements we recommend. Stay on course and you’ll start feeling better in no time!


The DNA test does not necessarily take into account your goals (e.g. breathholding, Ironman, cognition, etc.) and if your goals would benefit from ketosis, then you may want to choose it as a dietary strategy even though it could indeed be true that for FAT LOSS a higher carb intake may suit you. So it all depends on your goals. Or you could just us the supplements like ketones AND eat more carbs and get "best of both worlds".


“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.”
I am new to Keto, but not new to a low carb diet. I just started a keto diet 8 days ago. My goals for being on the diet is a little body recomp (nothing major, a few pounds of fat loss), and moving to fat as primary fuel for endurance with a focus on trail ultra marathon races and training. Along with Keto I am doing heart rate training using MAF and OFM as a guide. supplemented with body weight and free weight strength training and some HITT.
Wilder's colleague, paediatrician Mynie Gustav Peterman, later formulated the classic diet, with a ratio of one gram of protein per kilogram of body weight in children, 10–15 g of carbohydrate per day, and the remainder of calories from fat. Peterman's work in the 1920s established the techniques for induction and maintenance of the diet. Peterman documented positive effects (improved alertness, behaviour, and sleep) and adverse effects (nausea and vomiting due to excess ketosis). The diet proved to be very successful in children: Peterman reported in 1925 that 95% of 37 young patients had improved seizure control on the diet and 60% became seizure-free. By 1930, the diet had also been studied in 100 teenagers and adults. Clifford Joseph Barborka, Sr., also from the Mayo Clinic, reported that 56% of those older patients improved on the diet and 12% became seizure-free. Although the adult results are similar to modern studies of children, they did not compare as well to contemporary studies. Barborka concluded that adults were least likely to benefit from the diet, and the use of the ketogenic diet in adults was not studied again until 1999.[10][14]

Hi Ben great science & sound advice. May I share with the group? I’m 42, in australia, have been an alcoholic for 10 yrs. In April 2016 I gave up drinking & started living strictly ketogenic. In 3 months I dropped 25 kilos. I have cheated on weekends but I go through a fast of sorts on Mondays to get back into ketosis by Tues. I work afternoon / evenings so I wake at 10.30am take a pre workout drink with raspberry ketones & a splash of mct oil & all my vitamins as well. I then do weights for an hr then get ready to go to work. I take 2 800ml protein shakes consisting of 20 ml mct & 30grm amino enhanced protein. I work in warehousing so I walk anywhere between 10 km & 5 km a nite. I feel great all the time, thanks largely to your research & advice. If have any thoughts or opinions I’d love hear them.


It usually takes three to four days for your body to go into ketosis because you have to use up your body's stores of glucose, i.e., sugar first, Keatley says. Any major diet change can give you some, uh, issues, and Keatley says he often sees patients who complain of IBS-like symptoms and feeling wiped out at the beginning of the diet. (The tiredness happens because you have less access to carbs, which give you quick energy, he explains.)

So how does our body make ketones out of the stored fat?  First blood sugar and insulin have to be low enough to allow access to stored fat.  If they are, stored fat (in the form of triglyceride) can be mobilized as a fuel source. A substance called hormone sensitive lipase (HSL) breaks the triglyceride compound down into one glycerol molecule and 3 fatty acid molecules. These fatty acid molecules come in various lengths of carbon based chains.
When you burn key tones as a funeral, whether they are from a supplement or whether they are the ones that your body makes, you do indeed become more efficient utilizing ketones. So that is one advantage. You are correct in that if you simply use these and you do not restrict carbohydrate intake then you're not going to get quite as much benefit. I am a fan of combining these with intermittent fasting, MCT oil, and a high-fat diet.
One more thing that I noticed is that my HR does not move Beyond a certain point. I can still perform quite at a high level and faster than most people at my box but weirdly enough it’s like there’s a block on my HR which doesn’t allow it to move beyond 160 bpm. I’m not sure if this is good or bad! Could I go even faster if my HR would pass this limit?? It is a physiological barrier created by the glycogen sparing mechanism that doesn’t allow my body to move after a certain point so it won’t have to tap into my glycogen stores or force my body to go into gluconeogenesis?? If I added some more carbs around my workouts would it be easier to get the glycolytic pathway to work more effectively since it’d be faster and easier fuel? I read about the downregulation of PDH enzymes after prolonged keto and I constantly worry that I dont use my glycolytic pathway as effective anymore. I LOVE this lifestyle but at the same time, as athletes; we’re always thinking on how to improve performance. What are your thoughts?! Thank you so much!!
Adherence to a keto diet food list isn’t always great, though. A review published in January 2015 in the Journal of Clinical Neurology found that only 45 percent of participants were able to follow the approach as prescribed. “The poor compliance was attributed to side effects, social isolation, and cravings,” says Yawitz. And some people in the study “reported the diet simply wasn’t helping them lose weight,” she adds. Brissette agrees with this line of thinking. “In my opinion, the keto diet isn't sustainable and takes the joy and fun out of eating,” she says.
^ Greenberg CR, Dilling LA, Thompson GR, Seargeant LE, Haworth JC, Phillips S, Chan A, Vallance HD, Waters PJ, Sinclair G, Lillquist Y, Wanders RJ, Olpin SE (April 2009). "The paradox of the carnitine palmitoyltransferase type Ia P479L variant in Canadian Aboriginal populations". Molecular Genetics and Metabolism. 96 (4): 201–7. doi:10.1016/j.ymgme.2008.12.018. PMID 19217814.
Yes, they're technically a fruit, but we think olives deserve a shout-out all of their own, since they're also a great source of healthy fats and are one of a few keto-approved packaged foods. Plus, they're a great source of antioxidants, will satisfy your craving for something salty, and are blissfully low-carb. “About a palm's worth only has 3 grams of net carbs,” Sarah Jadin, RD, told Health in a previous interview.
The ketogenic diet doesn’t put a cap on saturated fat or even trans fats. The latter are fats you should always avoid. Read ingredient labels and avoid any food with partially hydrogenated oils, aka trans fats. These fats heighten your LDL (“bad”) cholesterol levels and lower your HDL (“good”) cholesterol levels. They also raise your risk of heart disease and stroke, according to the American Heart Association.
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.

If you remain under your optimal net carbs limit, then you should enter ketosis within 2 to 3 days. But it can take up to 7 days. The fastest way to get into ketosis is to exercise on an empty stomach, in order to accelerate the depletion of glycogen in your body. You can also do a Fat Fast for a few days (eating more fat) to speed up the rate at which you enter ketosis AND start to cut out refined carbs (like sugar) before you go for full ketosis. Another option is to do a water fast, (only drinking water) which also speeds up getting into ketosis.


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.


You’re transitioning. Your body is equipped to process a high intake of carbs and a lower intake of fat. Your body needs to create enzymes to be able to do this. In the transitional period, the brain may run low on energy which can lead to grogginess, nausea, and headaches. If you’re having a large problem with this, you can choose to reduce carb intake gradually.
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