Can You Drink Coffee While Fasting? + 3 Benefits Of Coffee Drinking


Taking on a water fast or intermittent fasting diet is inherently difficult because our bodies and brains are accustomed to a routine and periodic intake of calories and the taste of different foods and drinks.

Therefore, although most people understand that the premise of fasting involves abstaining from consuming food or caloric beverages, the option to have at least something other than water, especially during prolonged fasting or habitual intermittent fasting day after day, can be extremely helpful.

So, can you drink coffee while fasting? Does coffee break a fast?

In this article, we will discuss if you can drink coffee while intermittent fasting or doing a water fast, the “rules” around intermittent fasting coffee drinking, and if coffee breaks a fast.

We will cover: 

  • Can You Drink Coffee While Fasting?
  • Can You Only Drink Black Coffee While Fasting?
  • Benefits of Drinking Coffee While Fasting

Let’s get started!

A person holding a blue mug and smelling the aroma.

Can You Drink Coffee While Fasting? 

Due to the popularity of coffee drinking and the reliance on caffeine for a jolt of energy in the morning, one of the most popular questions among people adopting an intermittent fasting diet is: “Can you drink coffee while intermittent fasting?“

Technically, you should not eat or drink any caloric food or beverages while intermittent fasting or water fasting.

The primary purpose of fasting is to abstain from taking in any calories, forcing your metabolism to make use of stored energy for fuel.

Prolonged fasting can put the body in a state of ketosis, which involves burning ketones. Ketones are produced as a byproduct of the mobilization and oxidation of fatty acids.

Although in the early stages of fasting, glucose is produced in the liver through gluconeogenesis (primarily from amino acids), as more ketones are produced, and no glucose is coming in, the ketones replace glucose as the primary energy source in the central nervous system.

A person drinking a cup of coffee from a to-go cup.

If you end up consuming calories, especially carbohydrates, while fasting, you will be providing more glucose to your body, taking your body out of ketosis.

With that said, there isn’t a lot of research about exactly how many calories break a fast; in other words, you can likely consume a small number of calories without inducing any appreciable metabolic shift that will take you out of a fasted state or allow your body to start pulling from the new calories coming in for energy rather than from your fat stores or ketones.

Some fasting “experts” online say that as long as you stay under 50 calories, your body will effectively remain in a fasted state.

However, there aren’t really any research-based findings to substantiate this or overturn it, nor do these fasting experts define the timeframe under which you can have the 50 calories (Is it 50 calories in 1 hour? 50 calories in 24 hours? etc.).

A person stirring a cup of tea.

One cup (240 ml) of black coffee only contains approximately 3 calories, with just trace amounts of protein, fat, and minerals. Therefore, even a cup or two of coffee won’t really induce any metabolic changes or take you out of a fasted state.

In addition to drinking coffee while fasting, you can also drink tea.

Again, the same caveat applies here: it needs to be unsweetened herbal tea in cases where you are not supposed to have caffeine or unsweetened herbal, black, green, or other types of tea under a more liberal intermittent fasting diet.

It is important to note that with some of the stricter or more spiritual approaches to water fasting regimens, such as certain intensive 7-day water fasting protocols, caffeine is supposed to be avoided in all forms. 

This is typically done to help the body “detox“ or withdraw from the tolerance built up by habitual caffeine consumption, whether from drinking caffeinated tea, coffee, colas, energy drinks, or otherwise.

A person smiling holding a cup of tea.

If you are trying to reset your caffeine sensitivity and decrease your body‘s reliance on this stimulant, you may choose to drink decaffeinated coffee while intermittent fasting, but remember that even decaffeinated coffee does contain some caffeine

You might want to go with herbal tea instead, water, seltzer, or some electrolyte-enhanced water. 

Therefore, except in cases where you might be water fasting for religious or spiritual reasons or trying to do a prolonged water fast that also involves abstaining from caffeine, most fasting “authorities“ say that you can drink black coffee while fasting and that black coffee will not break a fast.

Intermittent fasting coffee drinking can help boost your energy when you cannot take in any calories and can provide a slight boost to your metabolic rate. 

Thus, if you are taking on an intermittent fasting diet for weight loss, intermittent fasting coffee drinking with black coffee may actually help augment your weight loss results and keep your metabolism humming at a good rate when calories aren’t coming in.

A cup of black coffee and coffee beans.

Can You Only Drink Black Coffee While Fasting?

Although non-caloric and artificial sweeteners don’t technically contain usable calories, most experts suggest eliminating all artificial sweeteners while intermittent fasting. 

This means that even calorie-free sweeteners such as Stevia, Splenda, Sweet and Low, sucralose, monk fruit extract, erythritol, and other sugar alcohols and noncaloric sugar substitutes should be avoided while intermittent fasting.

Moreover, although artificial sweeteners, sugar alcohols, and Stevia don’t contain an appreciable number of calories to really amount to anything, research is quite mixed on the metabolic effects of consuming non-caloric sweeteners

Therefore, it isn’t really clear how drinking black coffee with calorie-free artificial sugar substitutes while fasting will affect your body and metabolic state.

Again, unless you are following a strict water fasting protocol for religious or spiritual reasons or for a caffeine detox, there are no hard and fast “rules“ or laws surrounding intermittent fasting. You should make decisions based on what works best for you. 

A person smiling and holding a cup of coffee.

Therefore, even though the advice is to avoid all artificial sweeteners while intermittent fasting if you want to enjoy your black coffee with a dash of Stevia or a light sprinkle of Monk fruit extract for a little sweetness, you do you.

With that said, avoid caloric sweeteners such as sugar, brown sugar, sweetened creamers, etc., and you should not be adding milk, plant-based milk, cream, MCT oil, grass-fed butter, or other caloric add-ins to your coffee if you truly want to be fasting without caloric intake.

Once you start adding sweeteners and fats or milks, the caloric content of the coffee will increase significantly and will likely take you out of the fasted state.

It is especially important to avoid any sweeteners or plant-based milks or creamers that contain sugar.

Once you introduce sugar into the body when you are fasting, your body will preferentially select using the sugars and will stop burning ketones for fuel.

A cup of black coffee.

Benefits of Drinking Coffee While Fasting

There are several potential benefits of drinking coffee while intermittent fasting:

#1: It Helps Keep You Hydrated

Although water is certainly preferable from a hydration standpoint, many people doing long fasts find that drinking water gets boring.

As such, they may unconsciously not take in enough fluids, leading to dehydration. 

Dehydration is associated with many adverse health symptoms, including headaches, dizziness, fatigue, lightheadedness, difficulty concentrating, and low blood pressure.

Plus, dehydration decreases your metabolic rate and can make you feel hungrier, making it more difficult to abstain from eating.

By adding coffee, herbal tea, or seltzer to your repertoire of permissive drinks while fasting, you might be more inclined to drink more. Variety will help prevent palate fatigue and can encourage you to drink more fluids.

A person with a scarf on holding a cup of coffee between her two hands.

#2: It Provides Antioxidants

Coffee is rich in antioxidants, which are powerful compounds that can help your body combat free radicals, decrease oxidative damage, and decrease inflammation, supporting many of the same benefits of fasting.

#3: Coffee Can Boost Your Energy and Metabolic Rate

Caffeine is a stimulant, so it can increase energy, reduce fatigue, make you feel more alert, and can improve attention and focus. This can be helpful while fasting since your blood sugar can be low.

As mentioned, coffee can give you a moderate, temporary boost to your metabolic rate by about 3 to 11%. This can help you burn more calories.

Coffee may also help facilitate fat burning.

So, can you drink coffee while intermittent fasting? Overall, it’s up to you!

Black coffee does not break a fast and may give you energy and fluids to feel stronger through your fast, but if you prefer to stick to plain water, that’s great, too!

But what about after your fast? How do you break a fast, and with which foods are best to do so? Check out our guide, Here Are The 10 Best Foods To Break A Fast, for more information.

A frothy cup of black coffee.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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