I have been experimenting with a number of variations of bulletproof coffee over the past 2 1/2 months. After hearing this Joe Rogan podcast with Dr. Rhonda Patrick talking about the topic of intermittent fasting, I got curious if the use of bulletproof coffee could be integrated into this regimen. So, I searched for bulletproof coffee and intermittent fasting, and lo and behold, Dave Asprey has an article on this exact topic on his Bulletproof blog:

Bulletproof Intermittent Fasting: Lose Fat, Build Muscle, Stay Focused & Feel Great

In its simplest form, bulletproof coffee is just freshly brewed coffee with a tablespoon of grass fed butter in it. Dave recommends using a medium chain triglycerides product that he sells on this website called brain octane fuel or something like that. I have not yet tried that but I plan to after I do some genetic testing. More about that below. The term intermittent fasting refers to restricting the period of the day during which you consume substances that have caloric content to no more than an eight hour window. This means that you are fasting 16 hours every day. According to Dave Asprey, because bulletproof coffee only contains fat and no other sources of calories, the body responds as if you’re fast has not been broken. So, this type of intermittent fast is much easier to maintain, especially for those who are very overweight or obese.

I should disclose here that Dr. Patrick does not agree with this rationale. Dr. Patrick says one should not even drink plain coffee or tea during the fasting. However, Dr. Patrick indicated in the podcast with Joe Rogan mentioned above that she usually only fasts for 12 hours per day. This is in line with the research presented in her podcast with Dr. Satchin Panda on time restricted feeding. However, Dr. Patrick’s guest in a later podcast indicated that his research suggests only 16 or more hours fasting per day is adequate to get the full benefit.

Certainly, Dr. Patrick has at least somewhat more credibility on the subject than Dave Asprey does by the mere fact that she has a PhD and many peer reviewed publications under her belt. That being said, there are clearly several different interpretations of the research out there and it is unclear yet exactly how to proceed. I guess it’s time for a disclaimer. I’m not making any type of recommendation for anyone here. I am merely journaling my experience.

I know that I would not be able to undertake an intermittent fast unless I consumed the bulletproof coffee in the morning. For my intermittent fasting experiment, I’m using mushroom coffee and a tablespoon of Kerrygold grass fed butter. I’ve written about mushroom coffee previously. Dave makes a strong case in his blog for how the consumption of coffee contributes to the goals of those undertaking intermittent fasting. In in order to balance some of the conflicting interpretations of the research, I do not eat after 8 PM and do not have my bulletproof coffee until 8 AM. So, I am meeting the standard prescribed by Dr. Patrick of limiting my feeding period to 12 hours. However, if Dave Asprey is correct in his interpretation of the research, I am actually squeezing another four hours or more of fasting out of my day before I have my first meal that contains protein and carbohydrates. I may be losing some of the benefits that Dave describes because my actual consumption of coffee is about 50% lower than his recipe but I also get the benefit of the medicinal mushrooms. It remains to be seen whether my recipe is detrimental, neutral, or positive with regard to the goal of intermittent fasting.

There is a lot of controversy in comments section of the bulletproof blog about whether Dave’s recommendations are appropriate for all people. After listening to another podcast by Dr. Rhonda Patrick about personalized nutrition, I think the concerns of some of these commenters has merit. Dr. Patrick refers to a recent study called “Personalized Nutrition by Prediction of Glycemic Responses” that was published in a peer reviewed journal named Cell:


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The conclusion of the study is that genetic polymorphisms in combination with various lifestyle factors affect the response to different types of fats and the quality of the individuals microbiome. Based on your genetic heritage, you’ll respond very differently to carbohydrates and fats. So, there is not a one-size-fits-all solution to this problem. Some people do not have an issue excessive blood sugar response to carbohydrates and others have a blood sugar response when consuming fatty foods. I have not dug into the raw data myself yet, but Dr. Patrick says these genetic differences are closely tied to geographical ancestery regions.

I’ve studied the therapeutic nutrition systems and typical diets of a number traditional cultures as well as familiarized myself with many common modern dietary recommendations and the research that either supports or disputes them. All of the ancient cultures that had advanced therapeutic nutrition practices were agricultural societies and had been so for thousands of years before they began to write down their findings. Because they were agricultural societies, they relied on a diet that emphasized grains and usually also beans. The consumption of meat was variable. In Chinese culture, most people did eat meat but only in relatively small amounts as part of a diet that centered on grains and vegetables. In India, a large percentage of the population has been vegetarian for a very long time due to religious reasons. However, veganism was not common. The consumption of dairy and egg products was always quite widespread. The same pattern is present in traditional Arabic and Persian and northern African diets. You can also see this pattern in the typical diet of the agricultural civilizations of the New World like the Mayans, which centered foods such as turkey, corn, tubers, vegetables, beans.

From the perspective of epigenetics and genetic polymorphisms, one would expect descendants of people from these cultures to have a higher tolerance for consumption of carbohydrates then people who are more recently descended from communities who rely more on herding, fishing, or hunting than on agriculture for their sustenance than those in the larger urban centers did. Amongst those who are most recently descended from such communities are some Northern European Germanic peoples, Native Americans from North America, and south pacific islanders. Interestingly, these three groups have extremely high rates of diabetes when exposed to a high carbohydrate diet, especially one that contains refined carbohydrates and especially refined sugar and most especially, sugary drinks.

As a former practitioner of Chinese medicine who currently develops courses at a school of Chinese medicine, I feel that this is very important information that needs to be considered when giving dietary advice to patients. Many students, under the guidance of their clinical supervisors, tend to recommend dietary interventions that derive from traditional Chinese culture. Thus, there is a focus on a balanced diet that has a large component of grains but also includes a large amount of vegetables and a moderate amount of animal protein but not dairy. Such a diet might be problematic on one hand for a person of non-Muslim east Indian descent who may have a low tolerance for meat. However, even more likely is that such a diet will be counterproductive for those of native American heritage due to an excess of carbohydrates. However, all this speculation, interesting as it may be, is ultimately irrelevant. Your best bet is to get some genetic testing to determine your personal polymorphisms and use that to guide your dietary decisions.

Dr. Patrick has developed a tool on her website that allows you to do just that. You upload data produced by companies such as 23 and me to determine what type of foods will have the most positive impact on insulin production and the health of your microbiome.

The researchers in the study cited above were very focused on the quality of the individuals microbiome. Not surprisingly, one of the results showed that the benefits of fiber cut across all genetic types. I say not surprisingly because Dr. Patrick points out that the quality of the microbiome is an important factor in digestion and blood sugar regulation. Check out this pretty slick video overview of the study:


How does one ensure consuming enough fiber during the consumption phase of an intermittent fast? It is really important to make sure that you consume all of your daily required macronutrients during the consumption phase of the intermittent fast. You, of course, also need to consume all the necessary micronutrients, but that’s a different subject for a different day. This means that you need to consume enough protein and fat and carbohydrates, the ratios of which depend on your unique genetic polymorphism. So, while theoretically one could get a sizable amount of benefit by fasting 16 hours a day even if one is not particularly scrupulous about what one consumes during the consumption phase, you will not get nearly as much benefit if you do not attend to your microbiome. And, the most important factor in the health of your microbiome is an adequate amount of fiber in your diet.

Without taking fiber supplements, I am hard-pressed to see how one would be able to consume an adequate amount of fiber without some consumption of grains and beans, especially the beans. I do not think that most people would be able to stomach the amount of vegetables one would have to consume to ingest the necessary fiber. This actually runs contrary to the prohibitions on the bulletproof blog to stop consumption of all grains and beans. Raw nuts and seeds contain a decent amount of fiber and are also chock full of healthy fats and protein. Make them an important part of the consumption phase of your intermittent fast.

Here’s a detailed primer on fiber from Dr. Mercola’s website.

Many people may find it easier to consume large amounts of fruit instead of all vegetables to get their daily fiber, which brings us to the a discussion of the single most harmful factor in most peoples diets: refined sugar.

The relationship between sugar and saturated fat metabolism and heart disease is very well established at this point. The relationship between saturated fat alone and heart disease is weak. However, the consumption of many types of saturated fat in the presence of a high sugar diet is now known to be a key factor in heart disease. Dr. Patrick explains the research on the biochemical mechanisms for this in this podcast on refined sugar.

It’s amazing that we still have to say this and that people behave as if the jury is still out when the overwhelming research on the detrimental effects of sugar has been known for over three decades. The most important single dietary change anyone can make is to stop eating added sugar. According to Dr. Patrick, not all sources of sugar are equally bad for you. Small amounts of fruit are OK. Why is fruit OK? Because the presence of pectin and fiber offset most of the negative affects of the presence of fructose. However, it is probably still best to not go nuts on fruit. Other than fruit, there’s no form of sweetener that contains calories that has any nutritional value. They might taste good, but from the perspective of health, they are pure downside. This includes honey, so called raw sugar, coconut sugar, agave syrup, coconut syrup, etc. The only exception is Stevia, which has no calories.

Caveat 1: been Greenfield has some interesting thoughts on honey. Check out the section in his article on energy bars named “why honey is the perfect sweetener for a bar” here:


Caveat 2: I recently heard Tim Ferriss say on his podcast that he had asked one of his advertisers to formulate a special version of their mushroom hot cacao product that didn’t include any form of sweetener at all including Stevia because because even if it wasn’t a carbohydrate, it still had to be metabolized. This concern is similar to Dr. Patrick advising against the consumption of any tea or coffee during the fasting phase because they too need to be metabolized. Despite the lack of complete agreement and how to implement this very interesting research into one’s daily regimen, a few things are clear:

  1. There is strong evidence that some level of intermittent fasting is very beneficial to human health.
  2. Benefits appear to begin with 12 hours of fasting.
  3. Benefits become very pronounced after 16 hours and continue to increase there after.
  4. Taken together, there would appear to be only upside to experimenting with the simplest version of the intermittent fast, which would be not consuming anything that requires gut metabolism between 8 PM and 8 AM every day.

I’ll finish with one more disclaimer. Nothing that precede this should be construed as any type of recommendation. Proceed at your own risk. If you are seriously ill or pregnant, you should definitely consult with your primary healthcare provider before undertaking such a significant change to your diet.