Your Definitive Guide To Bulletproof Intermittent Fasting
By: Dave Asprey
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%. 
- It can improve cholesterol levels by reducing LDL (bad cholesterol) and blood triglycerides. 
- It gently stresses your cells, making them more resilient. [3,4] This includes neurons (brain cells). 
- It can also promote autophagy in your neurons – that’s when they get rid of damaged cells, toxins, and waste.  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. 
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)?
(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.
- 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!