Drinking coffee during intermittent fasting: the most important questions and answers

Kaffee trinken beim Intervallfasten: Die wichtigsten Fragen und Antworten

Do you have to do without your beloved morning coffee during intermittent fasting? There is still a lot of uncertainty about this question. The question arises whether the consumption of coffee has an influence on the health effects of fasting.

In this article we will enlighten you about it. We provide you with all the necessary facts about intermittent fasting and coffee. After that you will know if, how and when you can drink coffee during intermittent fasting and which alternative drinks are allowed.

the essentials in brief

  • In principle, coffee can be drunk in bulk during a fasting period. However, you should mainly enjoy it black and unsweetened
  • Black coffee may provide health benefits when fasting. Black coffee can support the self-cleaning mechanism of the cells (autophagy) that occurs with fasting and bring the body into ketosis faster.
  • There are many ways in which you can vary your coffee during the fasting period, even without milk and sugar.

Drinking coffee during intermittent fasting: what you should know

With intermittent fasting, you keep switching between phases of food intake, where you can eat everything, and phases of food restriction, where nothing is eaten.

There's absolutely no problem drinking coffee during your eating hours, as long as you're not consuming excessive calories or sugar. But what about the time when nothing is eaten? Does Coffee Affect the Health Benefits of Fasting? We will now explain this to you.

Can I drink coffee while intermittent fasting?

Basically, you can drink coffee during Lent. Coffee, if it is drunk black and without sugar, has hardly any calories. However, contrary to what is often assumed, coffee does not curb the appetite. On the other hand, coffee can support the positive effects of intermittent fasting, such as the self-cleaning mechanism of the cells or ketosis. (1,2,3)

But you shouldn't drink too much coffee. It should not be more than the recommended 2-3 cups per day. When you consume the caffeine in coffee, your body releases the stress hormone cortisol. This is a good thing in small amounts, but don't overdo it. After all, fasting is about letting the body rest.(3)

Cortisol has a major impact on metabolism and fat storage in the body. If you drink too much coffee, you can gain weight.

In addition, according to studies, the positive health effects of intermittent fasting are the same as those of calorie restriction. This means that it doesn't really matter in which fasting phase you drink a coffee. Much more important is how you drink the coffee.(4)

Can I drink coffee with milk during intermittent fasting?

You should avoid milk in coffee during the fasting phase. This is because milk contains lactose, which affects your insulin levels. It triggers glucose metabolism, which prevents you from losing weight.

This applies to cow's milk as well as cream. However, cream has less of an impact on your insulin levels because it contains more fat and less sugar. Fat burning is less affected.

Milk is poured into coffee

Black coffee alone contains hardly any calories. But if you add milk, you quickly get more. A cappuccino, for example, has about 80 calories. (Image source: Alberto Bogo / Unsplash)

With other types of milk such as soy milk, rice milk, oat milk or nut milk (e.g. almond, hazelnut or cashew milk) you should make sure that no additional sugar has been added. You should also not pour these into your coffee in large quantities, otherwise the calories will count. Burning calories distracts your body from regenerating cells and removing waste products.

type of milk effect on fasting
cow milk Not recommended because of the lactose and calories
cream Better than milk because less lactose
plant milk In small amounts and unsweetened

So adding a dash of milk to your coffee will certainly have an effect on weight loss or other health benefits of fasting. However, you can experiment with it, because every body is different.

How can I sweeten my coffee while fasting?

You should not eat sugar while fasting. Your body reacts to sugar and carbohydrates by releasing insulin. The body uses the sugar for quick and easy energy, and fat burning stops. If your goal is to lose weight, you should avoid it.

And what about other types of sugar? Alternative sweeteners overstimulate the sugar receptors on your tongue just like regular sugar. This has a major impact on how the taste of other foods is perceived.

This is anything but beneficial if you want to lose weight or eat healthy in general.

Nevertheless, the sweeteners do not have a strong effect on your insulin levels. However, how the human body and brain react to these sweeteners is very complex and in part still unexplored. There is still a lack of clarity, especially with newer sweeteners such as stevia or xylitol.(6)

Sweeteners increase your cravings for sugar. This is not exactly conducive to surviving a longer fasting period without any problems.

How else can I spice up my coffee?

There are many low-calorie and still tasty ways to make your coffee more interesting. Spices are particularly good for this. Many spices can even have an effect on your health. We have listed a few of them here:

  • Cinnamon: Cinnamon stimulates the metabolism, strengthens the immune system and helps to lower cholesterol and blood sugar levels.
  • Cacao: Cacao is said to lower blood pressure. Despite roasting, it is still rich in many ingredients such as magnesium, potassium and vitamin E and is a superfood that can contribute to better health. However, you should not take sweetened cocoa and not too much, because cocoa is high in calories.
  • Turmeric: Turmeric has a good reputation as an all-rounder. For example, it has an antioxidant, an antidepressant and even an anti-cancer effect.

At the moment it is also trendy to refine the coffee with coconut oil and butter. This type of coffee replaces almost an entire meal due to its high calorie content. If you are new to fasting and have decided to skip your breakfast, you can drink a coffee like this at first. This can suppress the feeling of hunger.

The fats it contains have a lot of calories, but have little effect on your glucose metabolism. This means that although you eat a lot of calories, you still have positive fasting effects. The blood sugar level does not rise uncontrollably because there are no carbohydrates and sugar. Fat burning continues.

We have a recipe for the so-called Bulletproof Coffee here. The best way to mix the ingredients is with a mixer.

  • 1 cup of coffee
  • 1 tablespoon butter or ghee
  • 1 tablespoon coconut oil or MCT oil
  • Season to taste (cinnamon, cocoa, turmeric, cardamom,...)

In the long run, however, this coffee is not recommended because it still has a lot of calories (over 400) and these calories contain hardly any nutrients.

How does drinking coffee affect the health benefits of intermittent fasting?

The health benefits of intermittent fasting are many. Here we explain how drinking coffee influences the effects of intermittent fasting.

  • Influence on ketosis: Ketosis is a metabolic state that can occur as a result of a ketogenic diet or fasting. The body gets its energy from body fat and forms ketone bodies in the blood. Intermittent fasting is a quick way to get into ketosis. The caffeine in coffee can even get your body into ketosis faster. (2.8)
  • Influence on autophagy: When fasting, autophagy sets in after some time. This is a self-cleaning mechanism of the cells. The cell breaks down defective or damaged proteins and organelles. This mechanism can be understood as a kind of recycling program, since the body also draws energy from it. Studies indicate, at least in mice, that coffee could speed up the triggering of autophagy. It doesn't matter whether you drink coffee with or without caffeine. (1)
  • Influence on insulin sensitivity: A positive effect of fasting is that fasting increases insulin sensitivity in the long term. High insulin sensitivity is conducive to weight loss. In the short term, however, insulin sensitivity is reduced during fasting. Studies indicate that this is similar with coffee consumption. Insulin sensitivity worsens acutely and improves over the long term. There are even studies that point to a link between coffee consumption and a lower risk of type 2 diabetes.(9,10)

Can I drink coffee on an empty stomach?

For many people, the easiest way to do intermittent fasting is to skip breakfast in the morning. But what if you don't take your coffee with breakfast in the morning but drink it on an empty stomach?

It is recommended to wait a few hours after getting up before drinking coffee. The stomach can be prepared for the coffee with tea or water first. In addition, it is generally better to drink coffee later in the morning. Before midday, the cortisol levels in the body are lower than in the morning and can be increased with a cup of coffee. Cortisol levels are naturally high in the morning (and that's a good thing). A cup of coffee increases the values ​​even more and puts the body under stress.

Woman holds her coffee

Coffee should not be drunk on an empty stomach. This can namely attack the gastric mucosa. (Image source: Maria Shanina / Unsplash)

What alternative drinks can I drink during intermittent fasting?

It is important to drink plenty of fluids during intermittent fasting, as your body normally absorbs a large part of the liquid from food and this is eliminated during fasting. Liquid also helps to suppress the feeling of hunger. With intermittent fasting you have to do without a lot of drinks. These include

  • alcohol
  • soft drinks
  • fruit juices
  • smoothie
  • Coconut water (naturally contains too much sugar)

However, we have also put together a small but fine selection of drinks for you that you can drink with a clear conscience.

  • Water: Water should be drunk in large quantities during the fast. If you want, you can enrich it with a little salt, since no salt is ingested through food when fasting. Drinking carbonated water while fasting is also okay. Another option is to make lemon or cucumber water.
  • Unsweetened Tea: Many types of tea offer health benefits. You can also enrich teas with healthy spices. There are also special fasting teas available on the market that can help with fasting.
  • Apple cider vinegar A drink made from a spoonful of apple cider vinegar dissolved in water is good for health. It has a positive effect on blood sugar levels, is good for digestion and prevents fatty liver.


So how and whether you drink coffee during the fasting period depends entirely on what your fasting goal is. Generally, drinking coffee isn't a problem as long as you don't overdo it. As long as you drink your coffee without milk and sugar, you are more likely to see health benefits. However, the study situation is not yet very clear.


  1. Pietrocola F, Malik SA, Mariño G, et al. Coffee induces autophagy in vivo. cell cycle. 2014
  2. Vandenberghe C, St-Pierre V, Courchesne-Loyer A, Hennebelle M, Castellano CA, Cunnane SC. Caffeine intake increases plasma ketones: an acute metabolic study in humans. Can J Physiol Pharmacol. 2017 Apr;95(4):455-458. doi: 10.1139/cjpp-2016-0338. Epub 2016 Nov 25. PMID: 28177691.
  3. Gavrieli A, Yannakoulia M, Fragopoulou E, Margaritopoulos D, Chamberland JP, Kaisari P, Kavouras SA, Mantzoros CS. Caffeinated coffee does not acutely affect energy intake, appetite, or inflammation but prevents serum cortisol concentrations from falling in healthy men. 2011
  4. Radhika V Seimona Jessica, Roekenes A, Jessica, Zibellini, Benjamin Zhu, Alice A Gibson, Andrew P Hills, Rachel E Wood, Neil A King, Nuala M Byrne, Amanda Sainsbury. Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials. 2015
  5. Martini D, Del Bo' C, Tassotti M, Riso P, Del Rio D, Brighenti F, Porrini M. Coffee Consumption and Oxidative Stress: A Review of Human Intervention Studies. Molecules. 2016
  6. Harris, Leanne1; Hamilton, Sharon2,3; Azevedo, Liana B.2,3; Olajide, Joan2,3; De Brún, Caroline2,3; Waller, Gilian2,3; Whittaker, Vicki2,3; Sharp, Tracey4; Lean, Mike1; Hankey, Catherine1,∗; Ells, Louisa1,3,∗ Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis, JBI Database of Systematic Reviews and Implementation Reports: 2018
  7. Lenoir M, Serre F, Cantin L, Ahmed SH. Intense sweetness surpasses cocaine reward. 2007
  8. Marwan Maalouf, Jong M Rho, Mark P Mattson. The neuroprotective properties of calorie restriction, the ketogenic diet, and ketone bodies. 2008
  9. Shi X, Xue W, Liang S, Zhao J, Zhang X. Acute caffeine ingestion reduces insulin sensitivity in healthy subjects: a systematic review and meta-analysis. 2016
  10. Kondo Y, Goto A, Noma H, Iso H, Hayashi K, Noda M. Effects of Coffee and Tea Consumption on Glucose Metabolism: A Systematic Review and Network Meta-Analysis. nutrients. 2018
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