So you’re interested in fasting, the health benefits it can provide, and how to do it.

But one concern is nagging you… Can you still have your morning cup of coffee while you fast?

It’s an important question. In our opinion, as fasting pupils and coffee lovers, one that deserves an entire article devoted to answering it.

Because food is one thing, but also having to give up your favorite morning pick-me-up might be a deal-breaker.

Does coffee break your fast? Or can you have your mug and sip it, too? 

Read on to find out (hint: it’s mostly good news).

Caution: Fasting is not for everyone, especially those who are pregnant or breastfeeding, under the age of 18, or have diabetes, low blood pressure, or a history of eating disorders. Please consult your doctor before starting a fasting practice.

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Does Coffee Break a Fast?

Before we can answer whether or not coffee breaks a fast, we should first define what "breaking a fast" actually means.

What "Breaks a Fast"?

Whether or not something ‘breaks a fast’ ultimately depends on 1) your fasting goals,  2) the type of fast, and 3) if that thing interferes with the benefits you want.

The benefits of fasting typically come from a specific process in your body being activated (“turned on”) or deactivated (“turned off”).

For example, if you’re fasting to improve body composition, you want to make sure insulin production is turned off so that you can utilize stored body fat for fuel. (More on this below.) 

So when it comes to coffee, what we’re really asking is: Does it activate the processes you want to be turned off during your fast, or vice versa?

If yes, then coffee might “break your fast.” If not, you can continue to have your daily cuppa, rest assured it won’t hinder your progress. Whew.

However, to provide clear answers to a somewhat complicated question, we’ve simplified a few things for this post:

• We’ll only address black coffee. Additives like cream, sugar, or sweeteners will be covered in an additional article.

• We’ll be answering the question “does coffee break a fast” for three types of fasts and goals. There are many different ways to fast and a variety of benefits to reap, but we’ll cover the most common here.

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The Three Most Common Fasting Goals and Methods

In this article, we discussed various ways to practice fasting and why there is no “best fast” for everyone. However, some fasting methods can help achieve certain benefits more efficiently than others.

Most people fast to improve one, or a combination of, the following:

• Longevity 
• Body composition
• General gut health

Based on the research, we believe the best fast for...

• Longevity is the non-caloric liquid fast (NCLF): Consuming only zero-calorie liquids.

• Body composition is intermittent fasting (IF): Fasting for 12-22 hours with no food intake.

• Gut health is the caloric liquid fast (CLF): Consuming calories only in liquids such as bone broth or smoothies.

Now that we have our fasting goals and methods defined, let’s answer the question, Does black coffee break a fast? for each. 

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Does Black Coffee Break an Intermittent Fast (Body Composition)?

One of the reasons intermittent fasting (IF) has become so popular is its ability to boost metabolic health, support fat loss, and improve body composition. Its effectiveness is likely due to its effect on insulin and blood sugar, a phenomenon Dr. Jason Fung has studied for several years. 

Put on your nerd caps with us for a minute as we explain how this works.

When we eat, the amount of glucose in our blood (blood sugar) will rise.

In response, our pancreas releases insulin, which among other things, facilitates the uptake of blood sugar into fat cells.

Insulin also inhibits our body’s ability to use fat as fuel.

When insulin levels are high, the body stores glucose as fat while simultaneously shutting down the body’s ability to burn fat.

What happens when the glucose runs out, and we need more fuel? Under healthy conditions, we dip into our fat stores for energy. 

This is the targeted mechanism of intermittent fasting for body composition. Fasting allows us to burn through our body’s glucose and utilize stored fat as fuel. 

All this to say, for something to break an intermittent fast, it will need to elevate blood sugar and insulin levels. 

For most people, black coffee does not elevate insulin to a level that will hinder stored fat utilization.

In fact, coffee can suppress hunger and increase fat oxidation, all of which may benefit body composition goals [1]. Coffee has also been shown to activate the Nrf2 pathway, a genetic pathway that turns on over 200 genes, many of which are related to detoxification and fat loss [2].

Caveat: For women, body composition-related results of fasting may vary (especially pre-menopausal women). Click here for the complete guide to fasting for females. 

Verdict: Black coffee probably doesn’t break an intermittent fast for body composition and likely enhances the benefits, at least for men. 

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Does Black Coffee Break a Caloric Liquid Fast (Gut Health)?

Fasting can make your gut stronger by giving it a rest from digestion, boosting its resilience against stress, increasing levels of good bacteria, and killing off harmful microbes [3]. 

(If you’re fasting for absolute gut rest, anything other than water will break your fast since you’ll be activating digestion to some degree. But the good news is you don’t need a complete gut shutdown to improve gut health!) 

To fast for gut health, you can still consume calories in the form of easy-to-digest liquids such as smoothies, bone broth, or juices. Ideally, your liquids also contain nutrients that are beneficial to your gut microbiome and intestinal lining.

And since coffee may have a beneficial effect on our microbiome, it is considered a gut health fasting friend, not a foe [4][5][6]. 

Caveat: If you experience any adverse effects from drinking coffee on an empty stomach, such as heartburn or acid reflux, you may want to forego the coffee during your fast (or opt for a cleaner coffee!).

Verdict: Black coffee probably doesn’t break a caloric liquid fast for gut health unless you experience gastrointestinal issues from drinking it on an empty stomach.

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Does Black Coffee Break a Non-Caloric Liquid Fast (Longevity)?

The benefits of coffee on long-term health are well-studied and show promise for daily coffee consumers. 

But is coffee safe to drink while you're doing a strict non-caloric liquid fast (NCLF)? 

That depends on whether or not it affects autophagy. 

Autophagy is a repair process in which cells cleanse themselves by removing old and damaged proteins, replacing them with new ones, and optimizing their function. This process has been associated with anti-aging and longevity because it keeps cells young, healthy, and functioning optimally [7].

So, does coffee interfere with this process of “cellular clean-up” that enhances longevity?

The research indicates that coffee does not appear to deactivate autophagy. On the contrary, a recent 2014 study conducted on mice showed that caffeine consumption and decaffeinated coffee actually activated autophagy in vivo [8]. 

In other words, not only does coffee likely NOT break a fast when it comes to longevity, it may even ENHANCE the anti-aging effects (probably due to the polyphenols in coffee, not the caffeine).

Verdict: Black coffee probably doesn’t break a non-caloric liquid fast for longevity and likely enhances the benefits.

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Does Black Coffee With Additives Break a Fast?

This is all great news for the hardcore black coffee drinkers, but what if you like your coffee with MCT oil, cream, sugar, or other additives? Does that “stuff” break a fast? 

Next week’s post will feature an in-depth look at the most popular coffee add-ons, foods, beverages, and supplements as we go deeper to answer your questions about what breaks a fast and why.

In the meantime, you can use the following questions to decide if your favorite coffee additives are invited to your fasting party:

• To figure out if it breaks an IF for body composition, ask: Does it elevate blood sugar? If yes, then it likely breaks your fast. 

• To figure out if it breaks a CLF for gut health, ask: Is anything in the liquid difficult for you to digest or detrimental to the gut? If yes, then it likely breaks your fast.  

• To figure out if it breaks an NCLF for longevity, ask: Does it have calories or anything that shuts off autophagy? If yes, then it breaks your fast. 

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Ki Points: Coffee and Fasting

Let’s recap: 

Most people fast to improve body composition, gut health, and longevity. And since many fasters are also coffee drinkers, people want to know: Does coffee break a fast? 

In other words: Does coffee interfere with fasting's benefits?

Good news: you can drink your black coffee and cash in on your fasting benefits — in fact, it actually enhances them.

So, go ahead and drink black coffee (responsibly, of course) and carry on fasting carefree…

Unless you drink poor quality coffee. 

Conventionally-grown coffee can contain pesticides, mold and mycotoxins, and acrylamide—things you typically don't want in your body while you're fasting—and can often lead to jitters and gastrointestinal distress when consumed on an empty stomach.

So if you’re going to drink coffee during your fast, you're better off drinking organic, mold-free coffee that provides pure, clean energy and high levels of polyphenols, without the jitters or upset stomach.

That's exactly why we've worked to source some of the healthiest coffee possible, Kion Coffee, to support you during your fast, and every day after that!

References

1. Harpaz, Eynav et al. “The effect of caffeine on energy balance.” Journal of basic and clinical physiology and pharmacology vol. 28,1 (2017): 1-10. doi:10.1515/jbcpp-2016-0090

2. Kolb, Hubert, Kerstin Kempf, and Stephan Martin. “Health Effects of Coffee: Mechanism Unraveled?” Nutrients 12.6 (2020): 1842. Crossref. Web.

3. Lara-Padilla, Eleazar et al. “Intermittent fasting modulates IgA levels in the small intestine under intense stress: a mouse model.” Journal of neuroimmunology vol. 285 (2015): 22-30. doi:10.1016/j.jneuroim.2015.05.013

4. Zhernakova, Alexandra et al. “Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity.” Science (New York, N.Y.) vol. 352,6285 (2016): 565-9. doi:10.1126/science.aad3369

5. Falony, Gwen et al. “Population-level analysis of gut microbiome variation.” Science (New York, N.Y.) vol. 352,6285 (2016): 560-4. doi:10.1126/science.aad3503

6. Ozdal, Tugba et al. “The Reciprocal Interactions between Polyphenols and Gut Microbiota and Effects on Bioaccessibility.” Nutrients vol. 8,2 78. 6 Feb. 2016, doi:10.3390/nu8020078

7. Longo, Valter D, and Mark P Mattson. “Fasting: molecular mechanisms and clinical applications.” Cell metabolism vol. 19,2 (2014): 181-92. doi:10.1016/j.cmet.2013.12.008

8. Pietrocola, Federico et al. “Coffee induces autophagy in vivo.” Cell cycle (Georgetown, Tex.) vol. 13,12 (2014): 1987-94. doi:10.4161/cc.28929