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Is Coffee OK During Intermittent Fasting?

Intermittent fasting (IF) is a modified eating approach that seeks to replicate the benefits of fasting but with a more moderate and achievable protocol.  IF benefits more than just your waistline; it also helps to stabilize blood sugar levels, reduce inflammation and keep your heart healthy.

So is coffee OK during intermittent fasting? The answer is, that it depends.

It actually depends on why the person is doing intermittent fasting. What are their goals? Are they doing it for weight loss or more for longevity and anti-aging purposes?

One basic question is what do they mean by coffee – just black coffee or bulletproof coffee, which often has butter, coconut oil and/or MCT oil. I think that bulletproof coffee is probably NOT a good idea for either goal, because of the high calorie count.

If someone is primarily doing it for weight loss, then plain black coffee, which has 0 calories, is fine. In fact, the appetite suppressing effects of coffee are probably beneficial.

If someone is doing IF more for anti-aging purposes then coffee is probably not a good idea. The reason is that even black coffee disrupts the process of autophagy which is the main way that intermittent fasting promotes longevity.

Autophagy is the self cleaning process by which the body’s cells break down and recycle damaged proteins and components. This is activated by intermittent fasting, but anything other than water (even black coffee) disrupts it to some extent. Autophagy is a very important process that was elucidated recently in research that was awarded the Nobel Prize in medicine.

The final caveat is that some fasting is better than none. So if having a regular or even bulletproof coffee is the only way that you can stick with the practice of intermittent fasting, then it’s probably worth it. What’s been your experience with coffee and intermittent fasting? Please share in comments below.



  1. Shea April 18, 2018 at 10:41 am - Reply

    I am practicing fasting for weight loss and anti-aging. I am hoping the autophagy helps with loose skin. I switched from BPC, to black coffee with Erythritol. I noticed my blood sugar spiking after consumption, so I switched the black coffee. This was huge for me. Unfortunately my blood sugar is STILL spiking 20-30pts after drinking black coffee. I am not diabetic, but I am insulin resistant.

    • Taylor May 6, 2019 at 5:15 am - Reply

      The caffeine in coffee is a stimulant which normally cause a spike in insulin…. that may be why you blood sugar is spiking.

  2. Holly May 11, 2018 at 1:58 pm - Reply

    I too have spikes with coffee. I do fatty tea in the am. I have experienced a calmer demeanor and less hot flashes. After eliminating coffee and switching to tea I did an experiment and added it back several days later, I felt horrible. It kind of clouded my head and gave me a stomach ache. Go Figure!

  3. Sandra Ruiz Prudencio June 8, 2018 at 5:54 am - Reply

    I have a question: Even green tea or Rooibos would disrupt it? I´ve been practising IF (16/8) for 2 years but I stick really good with black coffee.

    • oskyadmin June 14, 2018 at 9:54 am - Reply

      If the coffee helps you practice IF then stick with it!

      • Eva June 12, 2019 at 3:11 am - Reply

        I find having my regular coffee with cream and a little sugar satisfies me so much that I can go 20-24 hours without eating on IF and I am good. When I break my fast it’s usually with a high protein meal with no more than 10g or fat. I have lost weight and I have lost fat 😊

  4. Daniel Barras July 18, 2018 at 11:26 am - Reply

    Studies show exactly the opposite effect from coffee. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111762/

    • oskyadmin July 22, 2018 at 6:10 pm - Reply

      interesting study with animals – hope we get more human data soon – thank you for sharing!

      • Franck February 20, 2019 at 2:53 am - Reply

        Hello oskyadmin. We agree that studies with mice do not prove results (caffeine inducing autophagy) will be the same with humans. Yet it’s a good start to believe it will, when we see how efficient it is with mice on many organs (liver, heart, muscle..). But in your article you affirm the opposite as a fact : “even black coffee disrupts the process of autophagy”. Can you please name your sources ??? Thank you.

    • Shawn Kelly July 27, 2018 at 5:04 pm - Reply

      Thank you for posting the study link . Seems the whole coffee stopping autotphagy may just be so oft repeated that people are mistaking it for a fact.

    • jmr January 26, 2019 at 10:41 am - Reply

      This study is not showing the opposite effect, because the study does not look at the effect of coffee while fasting. They are not looking at the same scenario. Perhaps other studies have been made on this scenario, but I’ve not found one yet.

    • jmr January 26, 2019 at 10:44 am - Reply

      Daniel, this study does not show the opposite effect, because it is not looking at coffee consumption while also fasting. Fasting is not addressed at all in that study, and coffee consumption while intermittent fasting is what this article is addressing.

    • Michael June 5, 2019 at 2:28 pm - Reply

      There are no sources to support his statement. Rank conjecture and irresponsible.

  5. Vineeth Sastry August 8, 2018 at 3:28 am - Reply

    Sir, the question I cannot find an answer to is can I add sugar to my coffee and if so how much? Thank you

    • brian November 25, 2018 at 9:26 am - Reply

      no to sugar , only very small amount of milk or cream is acceptable. however i’ve watched this interesting youtube video

    • Mike S January 10, 2019 at 6:58 am - Reply

      I’m no expert but adding sugar likely detracts from IF and would be considered breaking the fast window.

    • Rhonda March 25, 2019 at 11:00 am - Reply

      Do not add sugar if you are fasting.

    • Jawanga Williams April 15, 2019 at 2:50 pm - Reply

      No sugar or creamer. Just black coffee, plain green tea, and water. That’s it during fasting period

  6. Amit January 15, 2019 at 11:36 pm - Reply

    > even black coffee disrupts the process of autophagy

    Sir, do you have any references to research studies about this?

  7. TAFANI FRANCK February 20, 2019 at 3:01 am - Reply

    Hello Sir, we agree that studies on animals do not prove the same results on humans. This being said, when we see how efficient it is on mice (caffeine inducing autophagy very quickly on liver, heart, muscle..) we can be confident for humans that at least it will not have negative effects. But you affirm the opposite : “even black coffee disrupts the process of autophagy”. Can you please name your sources ?? Thank you.

  8. Michael March 3, 2019 at 3:37 pm - Reply

    None of the comments on coffee stopping autophagy are in anyway supported by peer reviewed research. There is no evidence whatsoever to support the theory that black coffee has any negative effect on water fasting. If anything the opposite is true.

    • B October 14, 2019 at 9:26 am - Reply

      This so called “Dr. Akil” didn’t reply – he gives misinformation here that conflicts with published science. Black coffee induces autophagy, it doesn’t stop it. When another commenter gave the link to the study, “Dr. Akil” didn’t reply. Misinfo all over the internet by these quacks.

  9. Rhonda March 25, 2019 at 11:00 am - Reply

    You say coffee stops autophagy: where is the research to prove that? Everything I’ve read says the exact opposite. Here is one such research/study:


  10. Nina May 11, 2019 at 2:32 am - Reply

    I started Autophagy 16/8 hours .In the period of 8 hours of eating can I drink coffee?

    • oskyadmin May 14, 2019 at 7:33 pm - Reply

      Yes that should be fine.

      • Daizy Singh July 9, 2019 at 3:02 pm - Reply

        In that 16 hours of fasting can one have a black coffe if practising autophagy for weight loss? Please suggest

        • oskyadmin July 28, 2019 at 9:27 am - Reply

          Yes if the goal is weight loss that will not have a negative impact.

          –Dr. Akil

  11. Adam Heremaia May 21, 2019 at 2:55 pm - Reply

    The writer of this article said…” but anything other than water (even black coffee) disrupts it to some extent “…
    My understanding to this means black coffee may or may not…

  12. Kate May 23, 2019 at 11:50 pm - Reply

    Hi just wanna ask if 12hrs fasting is also ok or best if 16hrs fasting? Another question is it ok after fasting drink black coffee with unsweetened cocoa powder,Stevia and all purpose cream?
    Thank you

  13. Floriana Roccaro June 8, 2019 at 10:02 am - Reply

    I’ve read opposite is true on coffee stopping autophagy – I don’t think he has a source. I’m drinking black coffee and matcha green tea. Also mint hope that’s ok.

  14. Katie June 22, 2019 at 7:16 am - Reply

    Hi Dr Akil. I am new to IF and slowly working my way up to a 16 hour fast. I have a question about coffee with heavy whipping cream. I have been having black iced coffee with a tablespoon of heavy whipping cream and then having a 2nd cup usually less than an hour later with the same amount of heavy cream. Since 1 tablespoon of heavy cream contains 50 cal, does having 2 cups that close together break the fast due to the combination of the calories of the heavy whipping cream too quickly together?

    • oskyadmin July 28, 2019 at 9:28 am - Reply

      probably yes

  15. Lisa July 26, 2019 at 11:13 pm - Reply

    Looks like coffee is the sacred cow, most people cannot do without it and its addiction is greater than alcohol. Agree that coffee which has caffeine is unhealthful.

  16. Jonnie August 18, 2019 at 10:47 am - Reply

    I have been doing intermittent fasting for 2 years now, I have not had alcohol in 2 years or caffeine in any shape or form, my energy is balanced througout the day and i can run 4 miles in 28 minutes at 49 years old, the only thing I drink tea wise is red brush tea which is naturally caffeine free, the longest fast I have done was 45 hours anybody done longer ?

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