Why Bulletproof Coffee works

Why Bulletproof Coffee works

The Biology Behind Bulletproof Coffee

I will give a brief overview of how Bulletproof Coffee can be made and why you might want to make it. I will examine what biological mechanisms underlie the effects of the coffee recipe. 

 Why take my word for it?

I (Dagmar) have been drinking Bulletproof Coffee almost every morning (as my entire breakfast) for about a year now. I use the original (some would argue optimal) recipe for Bulletproof Coffee as described by Dave Asprey himself (more on that later). I also have a personal interest in the science behind why the coffee works the way it does. As a biohacker* myself, I am very interested in this topic and have gathered quite a bit of knowledge about the theory behind the Bulletproof Coffee recipe. I also have master’s degree in Biomedical Sciences, which has given me some insight into the main biological principles behind this coffee recipe.

*Someone who uses self-experimentation and personal data collection to optimise their biology, mainly to improve mental and physical performance, health and longevity.

Basics: What is Bulletproof Coffee?

Bulletproof Coffee is also know as butter coffee. It’s coffee with butter and coconut oil blended into it (with a blender). It tastes like coffee with a LOT of milk and has a creamy texture. This coffee recipe was originally formulated by Bulletproof founder and biohacker Dave Asprey, but has been adopted (and adjusted) widely since.

How do you make Bulletproof Coffee?

The basic recipe first, details later.

  1. Brew about 250 mL (or 1 cup) of coffee. This recipe requires freshly brewed coffee.
  2. To a blender (preferably preheated with some hot water), add:
  • the coffee you just brewed
  • 10-20 grams (or 1-2 tbsp) of butter
  • 15-30 mL (or 1-2 tbsp) of coconut or MCT oil
  • Blend together until a thick layer of foam forms (about 15-20 seconds in a high-powered blender)
  • Enjoy!

What can you expect from Bulletproof Coffee?

If everything works perfectly:

  • Consistent energy for the next 8-12 hours
  • No hunger
  • Excellent mental energy and concentration
  • Weight loss (if you don’t eat any carbs that day and have some excess fat to lose)
  • You will only need 1-2 cups of coffee per day


If things don’t work perfectly:

  • Upset stomach
  • Nausea
  • Diarrhea
  • Frequent restroom visits in general
  • Mental energy crash a few hours after drinking the coffee

Biology: Energy management systems

Before we continue exploring the benefits and potential side-effects of Bulletproof Coffee, you need to understand how your body handles energy first.

The human body has two main sources of fuel that can directly be turned into energy. With ‘energy’ I mean ATP (Adenosine TriPhosphate), the cellular energy storage molecule. ATP is produced by mitochondria within individual cells. Mitochondria require oxygen and substrate to produce energy. Substrate for mitochondria is made by breaking down glucose (sugars) in the citric acid cycle or fatty acids (maybe you remember this from high school biology classes). ATP can also be made without oxygen by converting glucose to lactic acid, but this is very inefficient compared burning glucose with oxygen. Excess amino acids not used to make proteins can be turned into glucose. This process is called gluconeogenesis (making new glucose) and can only be performed by the liver.

Burning Glucose

In theory, the body can burn both glucose and fatty acids to generate energy. In practice, the body uses one or the other, but never at the same time. Which type of fuel is used is regulated by hormones, which are mainly regulated by what and how often you eat. The main hormone of importance here is insulin, which is produced when blood glucose levels rise above a certain threshold. Carbohydrates raise insulin the most, followed by proteins (some types more than others). Eating fats will raise insulin very little or not at all.

Figure 01 – Fuel: carbs 

Insulin has many functions, but for now, we will focus on its energy management functions:

  • (1) Lowers blood glucose: increased glucose uptake by liver, muscle, and adipose (fat) tissues. In liver and muscle tissues, glucose is stored as glycogen.
  • (2) Promotes using glucose as fuel: insulin signals to all cells in the body that glucose is available to be used and is the preferred fuel source, over fatty acids.
  • (3) Promotes production of fats: increases the production of fatty acids and glycerol, which are needed to make triglycerides (fats). This process mainly takes place in the liver and is called liponeogenesis (making new fats).
  • (4) Promotes storage of fatty acids: insulin prevents adipose tissues from releasing fatty acids into the blood stream.
  • (5) Protein (muscle) breakdown: when the supply of glucose runs out (depleted glycogen stores), amino acids are converted to glucose through gluconeogenesis by the liver. Dietary amino acids are converted to glucose if more are available than necessary to make new proteins. Amino acids are freed up by breaking down cellular proteins, mainly from muscle tissue (This generally only happens after 12-24 hours of no carbohydrate intake).

Briefly summarised, insulin is an energy storage hormone. If it is present, you store energy. If insulin is absent, your energy gets freed up to be used. When insulin is present, you burn glucose. When insulin is absent, you burn fat.

Burning Fats

Most of the energy currently stored in your body is stored as fat, but it is only available to your cells if insulin is absent. So by now, you know how to prevent insulin production: by not eating carbohydrates, and not too much protein. However, you can still eat as much fat as you’d like.

Figure 02 – Fuel: fats 

In the absence of insulin:

  • (1) Fats are used as the main source of fuel: Some glucose is still used as fuel by red blood cells (which have no mitochondria and therefore cannot use fats to produce energy). All other cells will use fats as their primary fuel source.
  • (2) Fats are converted to ketones: When the liver is processing more fats than their mitochondria can burn, excessive substrates from fat breakdown are converted into ketones. Ketones are much smaller molecules than fat and cannot be converted back into fats. Ketones are water-soluble and released into the bloodstream to serve as an additional fuel source.
  • (3) Ketones are a highly efficient fuel source for mitochondria: Ketones provide an additional source of fuel, especially for brain and heart muscle tissue.
  • (4) Fats are released from fat stores in adipose tissue: Without insulin promoting fat storage, fats are freely exchanged by adipose tissue and blood cholesterol particles. Since fats are also being used as fuel, the output of fats from stores is greater than the input of fats into fat stores.
  • (5) Blood glucose levels are kept stable: with only a small amount of blood glucose being used, liver glycogen stores and occasional gluconeogenesis are sufficient to keep blood glucose levels constant. Even when glucose is not used as a fuel, it is still used in other biochemical processes and is therefore kept at a constant level.

An important aspect of fat burning is the production of ketones. When the liver is processing more fats in the citric acid cycle than the mitochondria can burn, the excess substrate is converted into ketones. Ketones have a bad reputation due to association with diabetic ketoacidosis (which is a serious health condition), but naturally occurring ketosis (nutritional ketosis) is not dangerous in the short term. Ketones are in fact a preferred fuel source for brain and (heart)muscles in the absence of glucose. In a state of nutritional ketosis, you can expect very high and consistent energy levels, excellent concentration and lack of hunger. Prolonged nutritional ketosis (months or years) can cause health problems, so generally cyclical ketosis is recommended. Just eat some carbs to step out of ketosis once in a while.

Why Bulletproof Coffee works

Now that you understand how the body deals with glucose and fats as fuel, it becomes much easier to understand why Bulletproof Coffee works.

Lots of energy and concentration

In the short-term, the caffeine from the coffee will stimulate you mentally, providing mental clarity and high concentration.

The coconut oil provides energy in the form of medium chain triglycerides (MCTs). MCTs are rapidly taken up by the body since they are more water-soluble than longer-chained triglycerides. Also, MCTs are almost immediately converted into ketones by the liver! More on MCTs later.

In the longer term (say, a few hours), the body will have taken up some of the fats from the butter and remaining coconut oil. If you drink Bulletproof Coffee in the morning and have not eaten anything that raises your blood glucose levels, your body will preferentially burn fat. The body starts burning fat while you are sleeping and continues to do so after you wake up (unless you elevate your blood glucose levels).

By adding more fats in the morning, your body will continue to burn fats. Fats burn very gently and slowly (no energy spikes or dips like with carbs or protein), so your energy will remain constant as long as fats are available. Remember, it does not matter to your mitochondria whether you just ate the fats or if they come from your fat stores. Fat will be available until insulin sends it back into the adipose tissue for storage.

No hunger

Hunger is a way for your brain to tell you that it’s running low on fuel. It entices you to eat something to replenish your fuel supplies. Unlike what most people think, though, you technically don’t need to eat every single day at set meal times. Humans, in general, can go for days without food (not saying that you should want to, but it’s an option). Fasting or not eating regularly gets easier when your body is used to burning fats for fuel (keto-adapted). When you are keto-adapted and you have some fat stored, your body will simply use your stored fat for energy when you are fasting. In a keto-adapted state, eating is driven more by habit (regularly schedules meals) than by a ‘need’ to eat.

When the body relies on glucose as its primary fuel source, we feel like we need to eat every 2-3 hours, because the food we eat makes us hungry! That is, carbohydrates and protein make us hungry. Remember how insulin stores energy (making it not available to be burned)? This takes available energy out of the blood stream (be it glucose or fats). When the brain notices the decrease in energy, you get hungry. If you eat something that raises blood glucose, your body produces insulin. Insulin then decreases available energy … you get the picture.

However, by not raising insulin (by not eating or by eating just fats), your energy won’t be put into storage and will remain constant. Without a feeling of hunger, I commonly forget to eat my (previously) regularly scheduled meals. (There will be a routine feeling of hunger at first during your regular meal times, but this should pass after 15 minutes or so if you ignore it and decrease over time).

Weight loss (if your body has stored excess fat)

This benefit goes back to insulin again (or a lack thereof). As I mentioned earlier, insulin promotes storage of fats while it is present. When insulin is not around, this fat slowly gets released into the bloodstream to serve as energy for other tissues. If insulin is present for long periods of time, the fat input is constant but the output is blocked. Think of like a bath tub or sink: you can pour water in, but if the drain is open, the water can still pour out at about the same rate. Insulin acts like a clog that prevents water from draining away. But instead of overflowing like a bath would, the body expands the size of the bath to fit the incoming water. Result: you are getting fat. Not a great long-term solution.

Don’t think Bulletproof Coffee can perform miracles! It will still take several weeks to months for your body to drain away excess stored fat on a perfect ketogenic (fat-burning) diet. However, Bulletproof Coffee will make it easier to sustain your chosen dietary adjustments if losing weight is your goal.

Why things can go wrong

There are some things you should be mindful off before fully embracing Bulletproof Coffee. Like any new food, your body will need some time to adapt to it.

Lots of fat

Bulletproof Coffee is generally not something most people will be able to tolerate right away (at least, not the high-fat/high-MCT recipe as described here). This is because it contains a lot of fat. The body might not be used to dealing with this amount of fat at once and will react negatively to it. Your digestive tract will be displeased and may start to eliminate the offending foods in either direction. This is especially true for MCT oil, but more on that later.

Solution: take it slow. Start by adding 5-10 grams of butter and the same amount of coconut/MCT oil. You can increase the amount of fat slowly over the course of a week or two. Otherwise … well, you have been warned.

Lots of MCTs

MCTs or medium chain triglycerides are special, short fatty acids that are found in, for example, coconut and palm oil. MCT oils are made from purifying coconut or palm oils (by taking other fats out). Not all MCTs are created equal and some can cause distress when taken in large quantities without prior adjustment. Overdosing on MCT oil will likely cause a condition Dave calls ‘disaster pants’ (aka rapid onset diarrhea).

Contaminated Coffee

If your mental energy craters after an hour or so, you can safely assume that the ingredients you used were contaminated with something that triggered your body’s immune system. An acute immune response causes a fight or flight response (by releasing adrenaline), which takes a large part of your energy and diverts it to your muscles and heart. This is to make you act quickly to oncoming danger. Likely, there is no real oncoming danger (if you were able to enjoy your Bulletproof Coffee earlier), so your body just wasted perfectly good energy for no real reason. If you pay attention, you might even feel a slightly (or not so slightly) elevated heart rate 30 to 90 minutes after drinking the coffee.

The most likely source of contamination is the coffee. As a product in general, it has a very high rate of being contaminated with mold toxins (mycotoxins). These toxins will trigger your immune system to react and launch a fight or flight response. Contamination may occur due to the use of low-quality beans or bad processing. Sensitivity to mycotoxins may vary between people, but negative effects are almost guaranteed. There are much more reasons to avoid mycotoxins as much as possible, but that is beyond the scope of this blog post.

Optimising your Bulletproof Coffee

Like any good biohack, you can personalise Bulletproof Coffee to a recipe that works for you. Learn more about optimising your Bulletproof coffee recipe by fine-tuning the variables coffee, butter, and coconut/MCT oil.

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