Hot coffee served with coffee beans.

Does Coffee Break a Fast? The Science Behind Fasting and Coffee

October 20, 20202 min read

With the amount of people who start their day with coffee, and the surging popularity of intermittent fasting, many are wondering: Does coffee break a fast?

Below I’ll cover whether coffee breaks a fast and other details related to coffee and intermittent fasting.



Does Coffee Break a Fast?

Technically, any calories “break” a fast. However, the fasting state can be maintained when you consume very few calories.

While a zero-calorie fast maximizes results, an extremely low calorie fast still provides substantial results.

“So, can I drink coffee while fasting?”

Black coffee, yes. A cup of black coffee has less than five calories and no carbs or protein, so it practically does not affect fasting.

For all other types of coffee, the sections below provide additional information.


Coffee and Autophagy

Autophagy improves overall cell function (improves overall health). If the goal is to enhance autophagy, you should consume very few calories during fasting.

If you are focused on autophagy, your coffee should have less than:

  • 25 calories

  • 3 grams of carbs

  • 1 gram of protein

Autophagy is delicate. The closer to pure black coffee you can get, the better.


Coffee and Ketosis

Ketosis improves fat loss (among other things).

If the goal is to maintain ketosis, you can consume some calories, provided they are mostly from high fat additions, such as cream, butter, or medium-chain triglycerides.

These additions will not take the body out of a ketogenic state, so you can add them to coffee without breaking ketosis.

If you are focused on ketosis, your coffee should have less than:

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As you can see, ketosis is not as delicate as autophagy. Still, the less additional ingredients you consume, the more benefits you will experience.


Which Types of Coffees Break a Fast?

Coffees come in many different styles. Below is a list of the 21 most popular types of coffee and whether or not they break a fast:

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Does Coffee Break a Fast Summary

Overall, does coffee break a fast depends on the reason for your fast (autophagy or ketosis), and the type of coffee you consume.

In general, fasting and coffee can coexist without breaking a fast. In fact, there may be synergistic effects when fasting and coffee are combined correctly.

To help create a proper pairing, remember that black coffee is best and if you have to add ingredients, limit calories, carbs, and protein.

Stephen Anton, PhD

Stephen Anton, PhD

Dr. Anton’s specific research interests are in the role that lifestyle factors have in influencing obesity, cardiovascular disease, and metabolic disease conditions. He completed his doctoral degree in Clinical and Health Psychology at the University of Florida (UF), receiving training in health promotion and the delivery of lifestyle interventions designed to modify eating and exercise behaviors. Following completion of his post-doctoral fellowship at the Pennington Biomedical Research Center in June 2007, he accepted a joint Assistant Professor position within the Department of Aging and Geriatric Research and Department of Clinical and Health Psychology at the University of Florida. Since joining the University of Florida, he has successfully obtained and conducted multiple grants examining the effects that lifestyle-based interventions have on biological and functional outcomes relevant to obesity, cardiovascular disease, and metabolic disease conditions related to aging. With over 150 scientific articles and book chapters, his research has been recognized both nationally as well as internationally.

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This information is for educational purposes only and is not a substitute for personalized medical advice. Please consult your physician before making changes to your health routine.