Your Definitive Guide To Bulletproof Intermittent Fasting

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Fasting has been around for centuries. In the last few years, a new spin on traditional fasting called intermittent fasting has become popular, and for good reason: not eating for anywhere from 16-48 hours (or longer) can profoundly impact your body and brain.

  •      Intermittent fasting increases lifespan in rats by 15-20%. [1]
  •      It can improve cholesterol levels by reducing LDL (bad cholesterol) and blood triglycerides. [2]
  •      It gently stresses your cells, making them more resilient. [3,4] This includes neurons (brain cells). [5]
  •      It can also promote autophagy in your neurons – that’s when they get rid of damaged cells, toxins, and waste. [6] Autophagy is partially responsible for the boost in mental clarity you may experience during intermittent fasting.

If you’ve tried intermittent fasting, you know that it works…and that it’s inconvenient because you run out of energy right in the middle of your day, and you don’t enter ketosis (fat burning mode) fast enough.

There’s a hack for that.

Here’s a way to upgrade an intermittent fast to make it easier and more effective with less effort. It’s something brand new and worth knowing about.

The Downside of Plain Intermittent Fasting

For all its benefits, plain intermittent fasting isn’t all sunshine and rainbows. Starving yourself for 18 hours takes extra effort. You get hungry. Distractingly hungry. With hunger comes loss of focus, grumpiness, and decreased productivity, and that’s no fun for anyone. There is actually a technical name for it, derived from Greek roots. It’s called “hypogly-bitch-ia”! 🙂

The reason for your hunger lies in two hormones: ghrelin and CCK. Your stomach and intestines release ghrelin when they want nutrients. Ghrelin then makes its way to your brain, where it sets off alarms telling you to eat. This little hormone is largely responsible for the sensation of hunger. When you’re 14 hours into a standard fast, your body is producing A TON of ghrelin, and you fritter away your day’s willpower saying no to it. But at least you’ll grow abs.

Along with ghrelin is cholecystokinin (CCK). CCK is the opposite of ghrelin, in a way, and is not manufactured by Calvin Klein. While ghrelin makes you feel hungry, CCK makes you feel full — so much so that injecting people with CCK mid-meal causes them to stop eating. [7]

When you’re on a generic intermittent fast, your “labrador brain” (see The Bulletproof Diet to learn what your labrador brain is doing when you’re not looking!) mistakenly senses that you’re starving to death and stops your body from producing much CCK. When your CCK levels drop, you no longer feel full so you start craving. Pair that with increased ghrelin and you’re left feeling famished, daydreaming about bacon instead of working.

But you’re not angry enough yet! Your body senses the lack of fuel, so it goes into adrenaline mode and secretes adrenaline and cortisol (you know, the hypoglybitchy hormone) in order to raise insulin and blood sugar levels. Those hormones give you energy but make everyone around you full of crap and annoying (on the other hand, they also help you burn fat when they aren’t chronically elevated).

Fortunately, there’s a hack for hunger and the hypoglybitchy “energy crash” state. You can manipulate your hormone levels to your advantage, so you feel full and focused the whole time you fast.

The key lies in Bulletproof Intermittent Fasting. This is something new, first published in the Bulletproof Diet, but derived from the work of Robert Atkins. Atkins described an induction diet that was high fat but contained inflammatory protein (casein). I experimented with using Bulletproof Coffee during an intermittent fast, which met the same criteria, except it had none of the inflammatory protein, and the fats were higher quality. The result was Bulletproof Intermittent Fasting.

Bulletproof Intermittent Fasting: Hack Your Hunger With Ketosis and MCTs

Bulletproof Intermittent Fasting is NOT intermittent fasting. It’s a whole new ball game. It lets you fast for hours without feeling hungry; it torches fat; it builds muscle; and the odd effects on your hunger are likely because it helps you into a hard to maintain biological state, where you’re almost in full-blown ketosis. You achieve this with one special ingredient in Bulletproof Coffee: Brain Octane Oil.

The normal way to get into ketosis is to eat zero carbs, moderate protein, and lots of fat for several days until your body switches into burning fat for fuel. When that happens, a blood test for ketones will read 0.8 (that’s mmol/L) or higher. You’ll never get there if you’re having moderate or even low carbohydrates. You’ll probably have levels of 0.2 or nearly none at all.

However, for most people, the right amount of Brain Octane can drive your blood ketone measurements to at least 0.5. It’s not nutritional ketosis, the aim of most ketogenic diets, but it’s way more than you can naturally get from just eating coconut oil or butter. And what a difference that makes!

If you can just dip into ketosis a little bit, you automatically reset your hunger hormone (ghrelin) and your satisfaction hormone (CCK).

The trick is getting deep enough into ketosis. Here are the stats:

  •      You can measure ketosis on a scale of 0.0 to >2.0
  •      The average person on an average day clocks in at around 0.1 to 0.2
  •      Both ghrelin and CCK reset at 0.48 or above [8,9,10]

The problem is that you’ll never hit those numbers unless you’re following a strict ketogenic diet, which shoots you way above what it takes to reset ghrelin and CCK. To get the benefits of Bulletproof Intermittent Fasting, you want to be in the Goldilocks zone for ketones – not too much, not too little, just right.

How do you exceed that magic number, 0.48, resetting your hunger hormones so you feel great while burning fat? And how do you do it if you eat carbohydrates (which I recommend on the Bulletproof Diet, but not all the time)?

Brain Octane oil!!

(Yes, I make the stuff so I can use it, and I am the one selling it. So feel free to take all the science in this post with a grain of (Himalayan) salt. It’s legit. Plain coconut oil just doesn’t work if you eat carbs, or I’d tell you about it!)

You may have heard of medium chain triglyceride (MCT) oil before. Chemists define an MCT as any fat with 6, 8-, 10-, or 12-carbon chains. The chemists ignored biology, because the body processes each oil differently, and 12-carbon fat (lauric acid) is not a true biological MCT at all. Coconut oil is only about 15% true biological MCT.

Brain Octane is different from generic MCT oil because it only contains the most effective fat, the rarest one with 8-carbon chains, which makes up about 6% of coconut oil. Your body converts them into energy much faster than it does chemical MCTs or saturated fats. XCT Oil is more affordable because it contains C8 and C10 and may work for you, although the C10 doesn’t peak as quickly.

Within minutes of consuming the right amount of Brain Octane for you, your body can process these fats, and your ketone levels can go into that Goldilocks zone where you have more ketones than someone who eats carbs, but less than someone on a ketogenic diet. That means you stop craving food, and you reset your hunger levels and feel full. Boom!

Best of all, if you consume fat while you’re fasting, but don’t eat protein or carbs, your body will essentially stay in a fasted state without raising insulin or digesting protein in the liver. You can still reap the benefits I list at the beginning of this article while avoiding major downsides.

To recap:

  •      Intermittent fasting is good for your body and brain, but it can be hard to do, and it tweaks your adrenaline levels to turn you into a hypoglybitchy troll, especially at 11am
  •      Ghrelin and CCK are the hormones that make you hungry or full and you can hack them
  •      Taking Brain Octane oil can send you into the goldilocks zone of ketosis, resetting your hormones so you stay in high-energy fat-burning mode without feeling hungry

Brain Octane is the key to Bulletproof Intermittent fasting. It’s life-changing stuff.

Can You Get Into Goldilocks Zone Ketosis Without Brain Octane?

Maybe. But it’s a lot harder.

  • XCT oil contains the C8 MCTs that are in Brain Octane, but it also has the longer C10 MCTs.
  • Your body takes longer to convert longer MCTs into fuel, so you don’t get the larger, immediate spike in ketones that Brain Octane provides.
  • Generic MCT oil often contains chemical MCTs that are processed in the liver like other fats, defeating the purpose, but it may work for you. You also have a much greater chance of getting “disaster pants” because of traces of C6 and C17 from manufacturing processes. (Generic MCT often comes from China and can have solvent-derived oils; Bulletproof makes ours in the USA without solvents)
  • Coconut oil contains some MCTs, and it’s great for you, but it doesn’t have enough C8 and C10 MCTs to affect your ketone levels much at all. You’d fill your pants and barf if you had 18 Tablespoons of coconut oil, but 1 Tablespoon of Brain Octane is easy!

In short, MCT oil could  save you money and get you enough into ketosis to curb hunger.  Coconut oil probably won’t get you into ketosis at all unless you’re on a zero carb diet.

Check out this post for more about Brain Octane vs. MCT oil vs. coconut oil.

Can You Get Into Ketosis Without Any MCTs?

Sure. It’ll take some time and effort:

  • You have to eat a very low-carb diet for several weeks, gradually training your body to burn fat instead of carbs.
  • Super low-carb diets dry out your eyes and skin by impairing mucous production.
  • They also decrease your sleep quality. That’s why the Bulletproof Diet includes a carb re-feed day once or twice a week (check out the Bulletproof Diet roadmap for free here).

Brain Octane is powerful enough to drive you into the Goldilocks zone even after you eat a bunch of carbs. You can have your cake (gluten- and sugar-free, hopefully), eat it too, and still wake up ready to burn fat and seize the day.

How Do I Know How Much Brain Octane To Take to reach the Goldilocks zone?

The short answer: you pee on sticks. Ketostix are sold online, as well as in most pharmacies. They change color according to the number of ketones in your urine.

Start with a small amount of Brain Octane – say, half a teaspoon – in the morning, preferably as part of a foamy cup of Bulletproof Coffee. Gradually increase the Brain Octane each morning, using Ketostix to check your ketone levels.

When you find a dose that gets your ketone levels above 0.48 you’re all set. Take that much every morning to curb your hunger and make fasting easier than ever before. It may take you a teaspoon, or it may take you two tablespoons. Just keep going up until you reach that magic 0.48 level. Don’t take too much too quickly, though!  If you jump the gun you risk disaster pants, and then nobody’s happy.

Have you tried normal intermittent fasting? What about Bulletproof Intermittent Fasting? I appreciate hearing about your experiences in the comments, along with any of your own tips and tricks. Stay Bulletproof!


Click to read the complete list of references.

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By Dave Asprey

  • PaulBNorris

    Just Few Days To Get Smart Deal with bulletproofexec…. < Find Here

  • Kwynne

    Is BP intermittent fasting just as healthy and beneficial for women as it is men? I have read (though not sure how credible) that it is not as healthy for women due to reproductive issues?

    • CC

      Dave addresses this in his Better Baby Book. I’m recalling from memory, so I may be slightly off, but he said women over 40 or women with a good deal of weight to lose don’t tolerate it as well.
      His hack for this is to add some of his collagen to your BP coffee. It breaks your fast, unlike straight bp intermittent fasting, but it is his suggestion for women in the above categories that aren’t seeing the results the want doing it without collagen.
      On a personal note, using the collagen has made the strength of my normally weak and peeling fingernails go through the roof. I can’t believe how great they look.

    • Jennifer

      Kwynne BP or regular intermittant fasting can cause strain on the adrenals and for some women it is a bad idea. For others it works great. I tried it for quite a while and did not get the great results so many claim to have achieved. If your hormones are out of balance (as mine have been) it may not be the best choice for you. My source of this information came from my NP, Dr Sara Gottfried and my own research. Hope that is somewhat helpful! I enjoy BP coffee but it didn’t help me lose any fat at all. My friend who is a triathlete tried it and she actually gained fat. And she doesn’t even eat carbs.

      I have not tried putting the collagen powder in the coffee. Perhaps that would make a difference.

  • lori

    Great post, very helpful! Ketostix measures in mg/dL… so what is the 0.48 mmol/L converted to mg/dL?

  • Shawn Jung

    Beware of disaster pants. I started BP IF with 1 ‘Tablespoon’ and had nightmare experience. It was traumatic. Start with 1 teaspoon!

  • wolverine1972

    dave thank u for opening my eyes to biohacking , but ur wrong you don’t have to buy mct-oil or butter you can fast using just bulletproof coffee and drink it around 2hr of your fast, and still not get hungry , and lose fat and build muscle

  • jackson

    this “in order to raise insulin and blood sugar levels.” is a contradictory sentence

  • Brain Octane is next level. I have MASSIVE focus when I use it compared to just regular BP coffee.

    You can add a little collagen protein to your coffee with Brain Octane to avoid the disaster pants issue.

  • chris

    Can Cacao be a part of the Bulletproof Intermittent Fast? Or would you suggest to leave it out of the coffee?

  • Stacey Chimilar

    I’m allergic to cow dairy and get disaster pants if I use butter in BP coffee. I can only use the oil. Can I use grass fed goat butter?

    • Kim

      I cracking up over the disaster pants. Thought it was just the men, but you mention it too. Can oil really make men not know when they need to get to the bathroom? Or am I misinterpreting the reference? Now I’m scared to try it!

    • Hi Stacey. Have you tried grass-fed ghee? Many people with dairy allergies have better luck with ghee because it doesn’t contain any milk proteins. Butter has a small number of these proteins, and they can cause problems for those who are particularly sensitive to cow dairy.

      • Ghee sounds great to try!

        What are the options if one is sensitive enough to cow dairy that ghee also causes reactions?

  • Nico

    I’ve been doing IF for 6 months and know all about the hunger at about 11am 🙂 I would love to get my hands on Brain Octane, but unfortunately it is not available in South Africa. Currently making my BP coffee with MCT oil and grass fed butter. It helps, but adding Brain Octane would be so much better

  • Kathy

    Would ketoforce and/or KetoCaNa with bulletproof coffee have a synergy for IF by making ketone levels go higher faster?
    (Assumes no budgetary constraints)

  • The Colbert Retort

    But how do you do it with Type II diabetes, and trying to manage your insulin levels?

    • Not sure whether I understand the question: low-carb/ketogenic should be switching the body over to burning fat/lipids as a fuel source, rather than carbs (which trigger the insulin/blood glucose dysregulation issues).

      Might be worth browsing Paleohacks, or blogs like Free The Animal for information on diabetes.

      There’s some extensive experimentation other diabetics have done (usually with carefully staying low-carb/ketogenic), many able to maintain blood sugar at normal (non-diabetic) levels without medication after awhile.

      Not sure whether Dave has some info on diabetes here, too. You can do a search via the search bar on this website.

  • ucntcme

    “But at least you’ll grow abs.” actually, you’re trimming away the fat that covers them. Showing your abs (the six-pack) is a process of removing the fat which smooths out the look thus covering them up. We all have the six pack, you just can’t see it without getting to low BF levels. For men, IIRC, you need to get down to 10% or lower. For women it is a bit higher, though I don’t recall the range at the moment.

    • CC

      I think everyone realizes that when Dave says he grew his abs, it is as a tongue in cheek statement. For the overly literal, that means, intentionally funny.

  • opal

    Sadly, even though I’ve been drinking BP coffee + brain octane and/or XTC oil, with collagen for months.. low to no carbs (salad for supper – I’m vegetarian) I have not lost an ounce. I love the coffee – don’t have hunger twinges until after 4pm or later, and do fit in that over 40 female that needs to loose a lot of weight. I’m |–| that close to lipo

    • All due respect, you may want to try adding seafood and/or grass-fed meats and such into your diet.

      Or, at least whey protein, but it’s doubtful that you’re getting enough fat % in your diet, and women all need more protein for their adrenals and hormones and bodily systems to function properly.

      If you’re eating a BP diet with no legumes, grains, etc., I can’t really see where the nutrients and (beneficial) calories that your body needs to run properly — and lose weight healthily — will come from.

      May be worth considering whether your health is more important than the reasons that you’re vegetarian, and trialing grass-fed, humanely raised beef for at least a couple of weeks.

      Or, at least *wild-caught* seafood and shellfish (or farmed, if oysters or mussels), if eating grass-fed ruminants is too objectionable.

      Your body really can’t healthily lose weight without nutrient-dense diet.

      If you have low-to-no carbs on a vegetarian diet, you’re probably not getting enough of a lot of macro- and micro-nutrients that your body needs to function.

      The list of foods that you’d have to choose from is just too small.

      The coffee is just one part of a lifestyle.

      It may work for some by itself in correcting obesity, but isn’t necessarily going to be enough for everyone.

      When you’re obese (meaning that your body’s systems are in all likelihood really dysregulated, and they need the proper nutrients and energy to start functioning properly again), it’s especially important to get proper nutrition.

      It’s like any other chronic illness in many ways. You have to get your body’s systems functioning properly in order to “heal.”

      Obesity is an illness of malnutrition, mis-nutrition, and dysregulated bodily systems due to other factors.

      Not calorie excess.

      Noticed you don’t list grass-fed butter in your morning drink, either – dairy allergy? Or, something else?

      Overall, based on the little bit of info you posted, you’re probably not consuming enough high quality fats and saturated fats.

      Or protein.

      And perhaps trying to induce a calorie deficit, not sure.

      • opal

        Thanks for the reply 🙂

        I am not entirely opposed to grass-fed beef or wild graised pork, except for the fear of more weight gain. When I began the vegetarian diet in 1994 I dropped 60 lbs in 4 months doing nothing else different. Any time I’ve attempted meat in the past 20 or so years I get the opposite of disaster pants. I’m guessing that the brain and XTC oils will help with that.

        fish and seafood on the other hand.. I just can’t. Evidently when I was really young, I got very sick (probably food poisoning) from seafood.. many days sick. I can’t even smell seafood cooking without getting queezy. Just the thought of it ..*urp – just no.

        I’m off beans (legumes) since around January but I do eat some organic nuts and seeds. I’m not 100% on the BP diet.. no reds from the chart but orange and yellow do appear.. how do people not eat garlic and onions and peppers???

        Most of the time I have organic hemp hearts in my dark green leafy salads – and I do eat cheese (grass fed.. amish – except for the occasional need for some parm on sliced tomatoes) I thicken soups with organic chia seeds and I will consume a good bone broth if I made it or someone I trust did.

        I put a big variety things in salads – not your standard lettuce, cucumber tomato salad here. I try to use all organic veggies.. especially the ones on the dirty dozen list.. and I do put cooked vegs in my salads sometimes.. well, cauliflower cooked in coconut oil and tumeric… I liked it raw but read somewhere that it should be at the very least steamed.

        I wish I could eat eggs.. had chickens and ducks for years.. I guess I over did eggs since now they cripple my intestines for the day when I eat them – in bed in a pain ball, crippled.

        I use a lot of supplements (C,D,Natto, dong quai, well a bunch more- and make yogurt smoothies with my salad supper(organic yogurt.. upgraded whey protein.. hemp protein, avocado.. pink salt.. cucumber sometimes.. switch it up depending on what’s in the house.

        I use the pink salt.. I use the blutathione force.. both the collagen products.. I prefer the gelatin one in BP coffee and I do use kerry gold (should be named kerry silver) in my coffee.

        I also cannot say that I don’t cheat.. once or twice a month I have a bad kryptonite cheat.. recees.. followed by coconut charcoal… and on my twice a week carb days it’s either organic long grain basmiti rice or yams – in my salad or soup.

        I do have a thyroid issue.. not hypo though.. multi nodual toxic goiter.. being treated – I think the meds may be keeping weight on me too.

        • Hrm, ouch on the food sensitivities and thyroid issue – my sympathies and empathy.

          I can’t have chicken eggs, either, although duck eggs seem to be alright with me.

          I laughed at the comment about garlic, onions, and peppers. They _are_ quite tasty. I don’t consume them myself because I notice the effects on my function right away. Sometimes having noticeable health-related reactions to foods actually helps. 🙂

          Shifting diet habits can be a bit of a process.

          The salads do sound a lot more nutrient dense than your typical paltry cucumber, lettuce, and tomato. The whey + yogurt, too. 🙂

          Was the meat you tried in the past, with the significant weight gain, grass-fed?

          I’ve had bad results personally with wild pork and conventional grain-fed ruminants and weight gain + sluggish function, while not overweight.

          But grass-fed is a whole different ball game in terms of toxin content, fat quality, omega 3: omega 6 ratio, and nutrition.

          There are many others with similar experiences with conventional vs. grass-fed ruminant meats.

          Not sure about the wild pork + weight gain – that’s a personal experience of mine and could have to do with personal food sensitivities. But, then, non-ruminant animals tend to have poorer omega 3: omega 6 fat profiles and more likely to be pro-inflammatory, especially if consumed regularly as staples.

          With the thyroid issue, what meds/treatment?

          Meds/treatments are complex. Have you looked into alternative med choices, if there are any? Some older generation meds (some of the ones used 20-40 years ago) can be less problematic.

          A Google search might turn up things, if you haven’t done extensive looking yet.

          I wouldn’t be surprised if the meds affect things, but glad to hear if the multi-nodual toxic goiter is being helped! That sounds quite unpleasant to have had to live with daily. Hopefully once treatment is over, without meds, your body can normalize. 🙂

          How are your adrenals and blood sugar regulation, given the thyroid issue?

        • opal

          Good morning. It’s hard to say re grass fed critters from the past since I quit eating meat in ’94 – I would assume conventionally fed while in the US. My majority of weight gain from the past was when I lived in Europe.. pastry.. pork.. chocolate… gravy.. cheese. No clue what they fed their critters back then.

          The treatment for my thyroid issue is methamazole..the more I weigh, the more I seem to need to control palpitations, swallowing issues etc.. I don’t think there is any other anti-thyroid med.. it’s been around forever too. It’s not a treatment that has an end though.
          I keep hoping that when I’m sporting less weight, that it might resolve itself but I keep going in the wrong direction there.

          I’ve looked into the natural alternatives and they deal with hyperthyroidism and Graves’ Disease, and hypothyroidism and Hashimoto’s Thyroiditis – not the presence of autonomous nodules – sometimes called plummers disease.. (that might have one M)

          The other “treatment” is to either kill my thyroid with radiation (big fat no) or surgically remove it… again, not thrilled with that prospect. While having way too much thyroid hormone being made, and needing a pill or two to control it seems bad.. not having any thyroid hormones and for sure needing a pill to survive for the rest of my life sounds worse.
          There are alternative treatment processes (alcohol ablation.. lasers) being explored but I don’t fit the criteria for the research studies (age, gender) – and they’re at the Mayo clinic .. and I’m in the south. One would think that if we could – with a laser, hit a fly, on the back of a cow,, from space – they could zap a few nodules with a laser instead of using radiation to kill the whole gland. *eye roll*

          My glucose levels are fine, if not a tad low sometimes – not sure if I’ve ever had a test for adrenals. Vit D levels . are good but I can’t recall the number but it was closer to the high number in the optimum range than the low.
          I was starting to loose some weight last year when I was juicing. .but life circumstances got in the way of that… and what I lost came back plus more when I stopped.
          I think I leveled off when I started the bullet proof coffee and intermittent fasting.. haven’t gained since but no loss either. Maybe I need to cut out the twice a week carb days.. which are still one meal days but with some carb portion in my salad or soup.
          It’s frustrating .. but that’s nothing new.

        • Gloria Cole

          Opal. I am trying intermittent fasting to “reverse diabetes” Type 2 but it seems to have triggered Grave’s Disease. I wouldn’t drop the methimazole (but check that you are on the lowest dose). You might investigate bugleweed to help lower the methimazole dose. The intermittent fasting I use is “window style” eating 10 to 4 p.m each day. That (or something) has triggered high morning bood sugar -cortisol based. So there is an insulin +adrenal thing going on, plus thyroid, gluconeogenesis, plus who knows what else? Anyhow IF did fix my diabetes. Now how to fix Grave’s Disease. Radio-Iodine Ablation was suggested. I ran out of the guys office, and will never go back there. You may not be losing weight because the IF is triggering its own blood sugar if your carbs go to low. It wears down your muscles. You do need some carbs–no junk. Also, nodules are there but if they are not cancerous, they are just symptoms. If you kill your thyroid to get rid of the nodules, you have really screwed up your endocrine system forever. The nodules will go away when you fix the autoimmune problem. (I hope that what I believe is true). I wish you the best, and empathsize with your situation.

        • opal

          hI Gloria .. Cheers! to running out of the office when faced with ablation. I’ll start reading up on the bugleweed.

          I was tested for Graves disease, early on with this nodule situation and was told that I don’t have that but Plummers (could be plumbers) syndrome. Nobody ever said autoimmune about my condition but autonomous was used regarding the nodules.. and they are benign – but functioning.. creepy, right? I think of them as little aliens living in my neck.

          My body does ok on IF for standard functioning – but I was pretty much doing IF before anyway.. coffee until I get hungry (which was mid afternoon) then one decent meal after a short snack (usually yogurt), I do miss my juicer juice* which was where I was getting fruit carbs.. since IF, I don’t have the sweet cravings for fruit anymore. I never thought I’d say .. need more carbs!

          Congrats on reversing your diabetes!

        • Gloria Cole

          Opal. i don’t know if Plummers is autoimmune. I guess you would have to be tested for antibodies. For any thyroid disease, you should be tested for iodine, and if low, correct with low doses of Idoral or lugols solution (J. Crow). You can O.D. on Iodine and usually its not recommended at all for hyperthyroid. But, you should use the test as a guide. Also you need adequate Selenium. (Brasil nuts) For autoimmune, the immune system is the problem –not the thyroid. So RAI for an autoimmune problem is not a good idea–instead you need to correct the weakened immune system. Eat for nutrient density. Get enough good fats and good carbs (antioxidant rich fruits and vegs) There are lots of protocols around for rebuilding an immune system. Leaky gut, mercury, stress, are frequent triggers. Yep. if you are overweight, IF should fix the problem. Dont forget fasting is not an excuse to eat junk. Breakfast is the meal that sets your energy level for the day, so if you don’t eat breakfast you are inviting trouble.

        • opal

          I’m guessing that your IF is a morning to afternoon window instead of afternoon to evening. 🙂 I do the BP coffee in the morning/afternoon and transition to food later in the day. Energy isn’t a problem. Ya know., I was eating Brazil nuts frequently when I was also juicing..I’m going to have to check around to see if my source for them is still viable.

      • Sonja Stendera

        Everybody will loose weight when reducing calories eventually. Otherwise anorectic people would not be thin and prisoners in the KZ would not have been either…

        • I’m going to try to be rigorous and challenge unclear thinking here.

          Is that due to lack of calories, or something else?

          Lack of macro or micronutrients, for example?

          I could also say it’s due to reducing green vegetables, or meat, or… whatever else is missing in those starvation diets, but correlation doesn’t = the cause. 🙂

          In otherwords, if I reduce X (in this case, “calories”) and observe y (in this case reduced body weight), I don’t know what else was also changed along with X which might’ve caused/impacted Y.

          So, x doesn’t necessarily cause y at all.

          I think there’s a -lot- of unclear thinking that tends to go on around diet, health, and lifestyle, and hopefully this got whoever is reading — the commentor I’m replying to, or otherwise — to think a bit more about that.

      • SamIAm

        This is some of the more confused blabber i have read in a while… not enough of a lot of macro nutrients? you are aware that there are only 3, right? Protein, Fat, Carbs… most of the micros come from plants, not from meats…

  • So, I do the Bulletproof Coffee with 1 T Brain Octane, 1 T Coconut Oil (I like the taste … ) and 1 T grass-fed butter. I have this at about 7 in the morning.

    With my old breakfast habits, I used to get hungry at around 11:00, but now I am getting hungry at about one. A bit inconvenient with the 9-to-5 job and everything, but ok.

    How long are we talking about fasting, here? If one gets the munchies early, would it be appropriate to have another Bulletproof Coffee (or maybe tea, to limit one’s caffeine intake during the middle of the day)?

    Right now, I am eating canned fish (tuna, wild salmon, sardines and sometimes mackerel) and nuts when I get hungry in the afternoon, but I’m not sure if this is giving me the full benefit of IF …

    Thanks for all the information. 🙂

  • Darryl Warren

    When I first began drinking BPC, I tried it on the cheap (coconut oil & GF butter only) and it worked well. Then I decided to give XCT a go. Holy ¢Rap! I live on a farm, went outside to work on plants, and next thing I knew it was 3 hours later.
    Definitely helps my energy level to go thru the roof, without the jitters associated with either too much coffee, or some illegal substance. 5 Stars from me.

  • Carmen Davis

    I just began BPC about a week ago, and I did get horrible disaster pants using just 1/2 tsp. of MCT oil. I don’t have a gallbladder (it was removed long ago), and I also have nasty heartburn issues (chronic). The BPC did give me heartburn, but not as bad as “regular” coffee with fake “creamer” in it. I’m wondering if the lack of a gallbladder has an impact on the disaster pants issue….for example, will it keep me from getting used to MCT oil? Would Brain Octane be better for someone like me? Would digestive enzymes help this issue as well as the heartburn? I want so badly for this to work! 🙂

    • JB Calgary

      Hi Carmen. I too, do not have a gallbladder and use 2 Tbsp of brain octane daily with no problems…but you have to work up to the right level s-l-o-w-l-y! The other issue is the health of your gut biome in general – get off of the inflammatory foods (grains) and feed your gut with the proper fermented foods, resistant starches and other good bacteria. Be patient… it will work!

  • Roxanne

    I started the intermittent fasting for the last 5 days. How long do I do the the intermittent fasting for? Or, is this permnament?

  • Adam Safron

    “Best of all, if you consume fat while you’re fasting, but don’t eat protein or carbs, your body will essentially stay in a fasted state without raising insulin or digesting protein in the liver.”

    Is there a citation you recommend for fat promoting protein sparing during fasting, or is this from personal monitoring of biomarkers?

    As I understand intermittent fasting, elevated growth hormone levels help promote fat burning while sparing protein. Although fat may be less insulinogenic than other foods, won’t it still raise insulin and so blunt the growth hormone response?

    Thanks in advance for your response.

  • Ollie

    I think there is a lot of bull. Dave Asprey is just trying to sell his products . I don’t have a problem getting into ketosis with the normal intermittent and LCHF diet .

  • Jaz

    Regarding the claim: “Both ghrelin and CCK reset at 0.48 or above [8,9,10]”… I am not seeing supported in any of the references. In fact, reference 10 says that C12 is most effective at stimulating CCK release, not C10 or C8. That would lead me to believe that coconut oil is more effective at suppressing hunger. Ref 10 doesn’t mentioned ketone levels at all, and the other two references are only available as abstracts. Anyone have any insight into the other studies and whether they actually substantiate the 0.48 claim? I love to see a study showing MCT vs coconut vs C8 oil and ketone production.

    • Anders Jonsson

      thanks for checking references, C12 is the thing then (for now) =)

    • Hey Jaz,

      From the results section of reference 8:

      “During the ketogenic VLED, subjects lost 13% of initial weight and fasting BHB increased from (mean±s.e.m.) 0.07±0.00 to 0.48±0.07?mmol/l (P<0.001). BHB fell to 0.19±0.03?mmol/l after 2 weeks of refeeding (P<0.001 compared with week 8). When participants were ketotic, the weight loss induced increase in ghrelin was suppressed. Glucose and NEFA were higher, and amylin, leptin and subjective ratings of appetite were lower at week 8 than after refeeding."

      BHB stands for beta-hydroxybutyrate, the major ketone body produced during ketosis. The study says that a BHB level of 0.48 mmol/l was enough to suppress ghrelin.

      A quick side-note: ketostix measure acetoacetate, another type of ketone body, and not BHB, but most people produce anywhere from 1-5 times as much BHB as they do acetoacetate, so if you hit that 0.48 mark with ketostix it's likely that you have at least that much BHB in your system.

      Reference 10 says that C12 is the most effective at stimulating CCK release, but C12 won't easily get most people into ketosis, so it won't reset ghrelin.

      C8 does stimulate CCK release (not as much as C12, but it's still significant; see ref. 10) and C8 has the added benefit of increasing ketone levels. That means it can both stimulate CCK and reset ghrelin. C8 is a double-pronged approach to curbing hunger, and that's why I use it.

      Hope this clears things up!

      • Jaz

        Ah, thanks! I didn’t equate BHB to ketone production, that’s where I got lost. Thanks for clarifying.

  • Mike Cheliak

    I have done IF before but haven’t for a while because of many of the things you’re mentioning. Mood, HANGRY feelings and then the inevitable “overeat” after fasting. I’ll be trying this method for sure! I love BPC and have found I am not really hungry but I eat breakfast anyway. Maybe I’ll try this slowly (8 hour fast to start) and see if my “break fast” is a bit more controlled.

  • Vicky Garcia

    I’m a vegetarian, but starting 5 five weeks ago, I changed my diet so that I consume no grains at all and my fruit intake has been next to nothing. I also started eating wild sockeye salmon and increased my consumption of eggs and nuts and good fats. I have 1 tbsp of coconut oil together with ordinary coffee in the morning and this has been enough to make me feel full all morning long. I don’t get hungry until the early afternoon. I eat A LOT of green leafy vegetables along with other low carb vegetables, and I only eat between 1pm and 7pm to promote ketosis. I do not need to lose weight but am trying to improve my memory and stay generally healthy. I have consistently been getting a ketosis reading of around 10 mg/dL in the mornings before I eat. I am wondering if this means that my body has now switched to using fat rather than glucose for energy. Would love to hear input on this.

    • here ìs how you can refill your bank account with addìtional cash every week. check my profile for more ínformatíon

    • SamIAm

      hate to break it to you…. you are NOT a vegetarian….

  • Alvaro Maurin

    Interesting post Dave. Let’s see a peer reviewed scientific publication to back your story up, and I’ll buy.

  • Disappointed fan

    Dave-Your marketing savvy is great, but your knowledge of keto-adaptation science is shallow at best and reveals that you’ll say anything to sell your overly expensive products. The only thing you are “hacking” is the wallets of gullible people. The readers on this blog would do well to read expert researchers in the keto-adaptation field like Phinney and Volek. You are putting out sadly inaccurate info and clearly will say anything to sell your products faking that you actually know what you are talking about…which you have made very clear that you don’t. Fat burning nutritional ketosis happens within a range of 1.5-3.0 for most people. It takes the brain and muscles about six weeks to keto-adapt and the kidneys another six weeks to go through keto-adaptation so they can switch over from excreting ketones and holding onto uric acid to excreting excess uric acid and retaining ketones. Keto-adaptation is basically switching over from predominantly being a sugar burner to a fat burner. Recommending ketone readings of .48 is spurious and is very far from keto-adaptation. Ghrelin and CCK are pretty minor players in keto-adaptation scheme of things. Who am I to take you to task? A quadruple board certified doctor who practiced research-based clinical nutrition for almost 4 decades and, in retirement from clinical practice, became a highly paid consultant and formulator for very successful (and ethical!) professional nutriceutical companies. I’ve also owned my own nutriceutical company and have a clear idea of the prices for raw materials. I know good products at fair prices and good science-based information when I see them. Your claims that your products are unique and somehow “hack” into human biochemistry better than similar, less expensive products are just not true. There is nothing exceptional about any of your products except their excessive prices. If your readers do a little research they can find equally good or better products available from reputable professional grade companies at more reasonable prices.

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  • Laura Riddle Wittke

    How soon after taking the Brain Octane Oil do you pee on the ketostix?

  • Hunger? Annoyance? Drink coffee. Problem solved ;]

    Caffeine from tablet dissolved in water would be even better, because coffee on empty stomach hits digestive system.

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  • Darci Frankel

    Hey Dave, is your collagen gluten free???

    The bars???
    I know, processed in a facility…. but

  • Is the idea of fasting basically to lose body fat? Otherwise why else bother?

  • DarkMagess

    So basically a trace rating of 5mg/dl is enough to be in the magic zone? That doesn’t seem right.

  • Melissa Quinones

    Hello Dave. I am currently 204 lbs and 5’5”. I recently lost 45 lbs during a 6 month period with exercise and eating right. However I gave been at this plateau for about 6 more months with no success. I tried the 16 hour fast which led me to lose 5 lbs in one week. My body is weak and need to re energize my mind and body without adding weight. I came across this information which intrigued me. I need help though. I’m not sure if this is for me. I have always been a muscular girl and I build muscle fast for some reason. The last I need is for more muscle to pack on. Will this Bulletproof fasting help to get lean muscle and lose fat as well?
    Also where can I get grass fed butter, or what butters do you recommend as well a she salt you mentioned for the fast. The Brain Octane oil I will purchase through the site. Hope to hear from you soon,

    • BobK

      I buy KerryGold Irish butter, it’s fantastic. You can even get it at Costco… it’s super yellow.

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  • Chad Smith

    No grass fed butter in the coffee on the fast?

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  • Nancy Brook

    Hey Dave – I have a question about BP intermittent fasting. I have been on a low carb diet and decided to incorporate BPC with brain octane and an 18 hour fast. I’ve been stalled with losing weight and thought this might help. The good news is that I did lose a few pounds already in three days. I did gain one back today. I tested ketones with blood strips today and I am at 5.2. From what I’ve read, if ketones get that high, your body thinks it’s in starvation mode. Should I back off the BPC since I am already on a low carb plan to lose weight?

  • Cindy Miller

    Hi Dave, I started BPC and IF 2 weeks ago and I’ve watched what I eat between 2-8. I’ve noticed that I’ve had a slight headache ever since. I’m also still hungry! I just ordered Brain Octane and I’m hoping that helps. I also just bought Trueplus test strips and Walgreens but the numbers on the chart go from 0 to 160 and I’m at about a 20. I used a converter and it said I was at a 1.11mmol/L. Is this correct? So I am in Ketosis?

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  • Ashley

    I drink bulletproof coffee before my 6 a.m. crossfit workouts, and I feel great during the workout, but I’m wondering if I should still refrain from eating until the afternoon if I am doing intense morning workouts. Can someone please shed light on the best way to incorporate intermittent bulletproof f
    fasting with early morning intense exercise? I would be very grateful!

  • Ashley

    I drink bulletproof coffee before my 6 a.m. crossfit workouts, and I feel great during the workout, but I’m wondering if I should still refrain from eating until the afternoon if I am doing intense morning workouts. Can someone please shed light on the best way to incorporate intermittent bulletproof fasting with early morning intense exercise? I would be very grateful!

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  • Sara Ross-Gill

    how many cups of the coffee can you have a day?

  • Gustavo Hess

    Is it possible to take the Brain octane oil alone and have the same results? I do intermittent fasting but i’m vegan and I also don’t drink coffee. Would love to see your take on this.

    • One day I had no coffee so I did a SHOT of brain octaine. One Tablespoon. It was not that disgusting and yes, it kept me full and focussed. A great tip.

  • paiger406

    Hi. I’m new to Bulletproof as a way of life (my book is on the way!) Can I do Bulletproof Intermittent Fasting every day? I think I read something about adding protein in some cases, but I’ll get more into that when I read the book. Thanks!

  • Shellie Becker

    I hate the taste of coffee. Anything I can add to make it better?

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  • Krysti Pashby

    I am doing the bullet proof diet. I am having the coffee in the morning and eating about 2. I am usually still hungry after 1 TBS of the octaine and 1 TBS of butter. So I have another cup around 12:00. Is that too much? I do not have a pants problem lol.

    I have had a headache for several days now. Why?

    If I add why protein or collegen protein in the am then my ketosis will STOP? Is this right? I am trying to be healthy but need to lose the weight.

    I am 37 and 150lbs. I dropped inches but can’t seem to lose any weight. What am I doing wrong?

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  • sunnyside

    I listen to your podcast and I visit your SM location for food and coffee….. it is a bit overwhelming trying to distill the information into quick and simple action points. We have busy lives, I can’t sit and read a whole book or distill down the details in the podcasts….or watch full lenght videos while I am driving or walking.

    I am happy to buy the products, but the information just takes too long!

    I need bulletpoints! The recipes to Bulletproof Intermittent Fast, the hours, the lenght of days, the food for the breaking time? I assume I am missing something obvious, like a page in the book?

  • Courtney James

    I do practice intermittent fasting after a fashion. My feeding window is at most 8 hours long (from 12:00 noon until 8:00 PM). Sometimes my feeding window is smaller because I may start eating later than noon and/or finish my last meal before 8:00 PM.

    I had been doing this for several months but, starting one month ago, I’ve made a change. I don’t eat at all on Mondays, Wednesdays, and Fridays; I just drink filtered water. So, during the week, I have a 6 to 8 hour feeding window followed by 40+ hours of fasting. Luckily, I have never experienced the “hypogly-bitch-ia” described in the article. So far, I feel really good. I feel especially great in the morning after my full day fast. I feel light, both physically and emotionally. My thoughts are clear and I feel energized. It’s only been a month so far and, if I continue to feel as good as I do now, I plan to keep going perhaps until the end of the year then re-evaluate.

    A little about me. I have been vegan for a while (close to 3 years I think). Before that I was a vegetarian who occasionally ate eggs, yogurt, and cheese. I haven’t eaten meat since 1980. After 36 years I cannot imagine eating meat again, but I am still intrigued by the Bulletproof regimen. The last time I drank coffee was probably more than 30 years ago. I didn’t dislike it. It simply didn’t appeal to me.

    I have a few questions.
    1. Are there any vegan/vegetarians here who follow the Bulletproof diet except for eating meat? Is such a thing even possible?

    2. Is there Bulletproof Tea? If so, how does it compare to the coffee in terms of effectiveness?

    3. Is the Brain Octane effective on it’s own without the coffee and grass-fed butter? My brain feels good with the intermittent fasting but I would still like to increase the beneficial effects.

    Thanks a lot.

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  • Question: I do the intermittent fasting, from about 7pm-12pm the next day, and I drink Bulletproof coffee + Brain Octane + Unsalted Butter in the mornings (I also include Collagen Protein).

    Is that all I need to do, or did I miss something above? Thanks!

  • Caroline Nie Ohuchi

    I have been drinking bulletproof coffee but also I add the collagen. Does that mean I am not doing the intermittent fasting if I add collagen to it? I also add organic coconut milk to it plus grass fed butter and brain octane.I have started about 1 month. My weigh doesn’t go down at all.

  • pixelzombie

    I find that eating my last meal at the very end of the 8 hour cycle works just fine. I feel hungry at times but nothing I can’t deal with.

  • Dale Myers

    Very curious, I am following the Ketogenic diet to about 90% accuracy. Although, I am curious what model to follow based on blood work in order to be at peak performance on the diet. I need to get my triglycerides tested to make sure its not going up. Per DOM triglycerides should not increase if they do it may not be safe to be on the diet. Any feedback is appreciated.

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  • Zano Tyrannis

    Hi Dave i love the podcasts and all the info. Thank you.
    I am trying to figure out how to combine IF with SANE eating. I train every morning on the body for science program. How can i optimise my results?

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  • Jake

    I was just wondering if there was any abswers for the questions asked?

    • Johnny Bravo

      Nope it’s just buy my stuff and figure it out yourself. Just by his snake oil.

  • Jason Cicchelli

    Due to the 5 grams of carbs within each one, is it fair to say that one can’t do Bulletproof Intermittent Fasting while using the Instamix packets?

    • Johnny Bravo

      Oops, you figured that out. Don’t say it to loud.

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  • Musa Vadnais

    I am interested in the answer to the question posted on the time period for testing.

  • Bruna Bozzetto Closs


    I just ordered the Upgraded Brain Octane Oil to help me get through my fasting days.
    However I’m in doubt about the other days, when I can eat. I’m not following a ketogenic diet, and on eating days I get to eat some carbs (slice of bread, brown rice or pasta, or veggies). Will I still reap the benefits of fat loss? On my eating days I don’t get over 1.500kcal.


  • ProfessorMike

    So I am interested in trying this but I am confused. Do you do this every day or just a couple days a week? Many commentators talk about “my fasting days.” If this is true, are you all IF on days that you do not work out? Thanks!

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  • Love what your doing here. Ive been using IF for years and it has given me a new lease on life. How have you been dealing with cravings or weakness when you work out or exercise in the fasting phase.

  • David Kurtz

    Just a few questions:
    1. Can you adjust the time frame? I typically get out of bed around 3:30, if I eat my last meal of the day @ 6:00 PM, an 18 hour fast would allow me to eat at noon the next day.
    2. What affect does physical activity have on fasting? I go for a 3.5 to 5 or 6 mile run, usually at 4:00 am, 3 to 4 days during the week, and 6 to 7:30 (anywhere from 8 to 15 miles) in the morning on weekends.
    3. My normal training routine calls for a recovery shake within 1/2 hour after my run. I have eliminated most carbs from the shake. I use coconut or almond milk, kale, whey protein, and frozen blueberries in the shake. If I don’t do the recovery shake, can I eat before the 18 hours?

    • Debbie Patterson

      what I have read on this topic is yes you can adjust the times you start and stop the fast…sometimes I fast 16 sometimes 18 sometimes I start at 6 sometimes at 8, it depends on my schedule. As far as exercise, I was told by my ketogenic Dr. it is best to exercise right before you break the fast.

      • David Kurtz

        Thanks Debbie!

  • Debbie Patterson

    I have been using bullet proof intermittent fasting for several weeks now, close to two months, and I tried to go one day without the coffee and all I could think about was food, and I could not sustain the fast! PLUS I normally eat bullet proof, so I am low carb eater. I did make a mistake of drinking two or three cups of bullet proof during the day, which stalled my weight loss, so I trimmed it down to 1 cup BP each day (2TBSP Brain Octane & 2 TBSP Grassfed Ghee) and I am able to very easily fast from 6 or 7 pm in the evening until 1 or 2 pm the next day. The weight is coming off fast!!! Amazing! This really does work magic on our bodies, thanks for all your research!

    • Kim Abplanalp

      When do you drink your coffee?

  • richnash33

    I drink my BP maybe a little bit different. I make 2 cups , add in 3 TBS of grass fed butter and have worked up to 3 tbs of Brain Octane and pretty much sip on it while at work from 8 am to around 11:30. This being said I find myself hungry about an hour later on some days. Is this normal? Should I add even more brain octane oil and or butter? I should add the rest of my diet follows bulletproof guidelines.

    • rehanift

      I had the same issue. I found that drinking 1-2 liters of water during the fasting period helped me easily make it into the late afternoon before getting hungry.

      • richnash33

        Thanks that makes sense. I wasn’t sure if because I was getting the brain octane on a slow drip so to speak as opposed to having it all at once could make a difference.

    • Johnny Bravo

      So six hundred calories of pure fat? Which doesn’t even taste good. Because nothing good for you has to taste bad. Snake oil being sold here. Brain octaine is only the new go to super ingredient. It’s just coconut oil processed at a high price.

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  • Johnny Bravo

    In the morning is best.

  • Kim Abplanalp

    Hi. I’m confused by what you write here vs in your book you recommend adding protein (like collagen protein,) to my bulletproof coffee if I’ve got a lot of weight to lose?