Updated: October 2026
In short: Black coffee without milk and sugar is allowed during intermittent fasting: a cup has so few calories that it doesn't break the fast. Milk, cream, sugar and syrup, on the other hand, provide energy and, strictly speaking, end the fasted state. If you have stomach problems, are pregnant or take medication, it's worth keeping an eye on the amount. As of: October 2026.
For many people, the morning coffee is the hardest part of fasting. Here's what works during the fasting phase, where the line is and what you can drink instead.
Can I drink coffee during intermittent fasting?
Yes, as long as it stays black. The AOK (a German health insurer) lists water, unsweetened tea, black coffee and thin vegetable broth as drinks for the fasting phases. Healthline puts a cup of black coffee at fewer than 3 calories. According to that analysis, one or two cups aren't enough to noticeably switch your metabolism.
What matters is your goal. If you're after a rhythm like 16:8, coffee often helps bridge the fasting hours in the morning. If you're after a strict fast without any energy intake, water and unsweetened tea remain the safe choice here too. You'll find more on the methods in the article What Is Intermittent Fasting and What Are the Rules?
What breaks your fast in coffee?
Anything that provides calories. Milk, cream, sugar, honey, syrup and oat drink bring energy and carbohydrates, even if it's just a splash. Healthline points out that some people add small amounts of milk or fat to take the edge off hunger. Technically that breaks the fast, even though, according to some experts, ketosis may continue.
The table shows how you can classify your coffee:
| In your coffee | Fast broken? | Assessment |
|---|---|---|
| Black, nothing added | No | Fewer than 3 kcal per cup |
| Cinnamon (pinch) | Mostly no | Hardly any calories, but the taste stimulus can trigger appetite |
| Milk or cream | Yes | Provides energy, strictly speaking ends the fast |
| Sugar, honey, syrup | Yes | Carbohydrates, insulin response |
| Butter or coconut oil | Yes | Fat, high in calories despite the small amount |
| Latte, cappuccino | Yes | Lots of milk, counts as a meal |
The cinnamon row is our own assessment, not an established rule. If you want to be on the safe side, leave it out.
How much coffee makes sense while fasting?
No more than usual. The EFSA considers up to 400 mg of caffeine per day safe for healthy adults, spread across the day, and single doses of up to 200 mg. Healthline cites around four cups as the limit beyond which sleep problems, restlessness and digestive complaints become more common.
On an empty stomach, caffeine hits many people harder. An example for a 16:8 day with an eating window from 12 to 8 pm, as the AOK also describes:
- 7 am: large glass of water
- 8 am: one cup of black coffee
- 10 am: herbal tea or water
- 11 am: second cup of coffee, if you like
- 12 noon: first meal
Two cups before eating are well tolerated by most people. After that, it's purely a matter of taste.
Keep an eye on the dose: if the EFSA classes single doses of up to 200 mg as safe, you shouldn't use up the daily limit of 400 mg in two big mugs in the morning, but spread it across the day. That applies to fasting just as it does otherwise.
How do I get through the morning without a milky coffee?
By switching gradually rather than going cold turkey. Many people don't struggle with intermittent fasting because of hunger, but because of the habit of starting the day with a sweet milky coffee.
| Week | Your coffee in the fasting window |
|---|---|
| 1 | Leave out the milk, only have milky coffee in the eating window |
| 2 | Cut out sugar and syrup completely |
| 3 | Limit to two cups of black coffee |
| 4 | Replace one cup with herbal tea |
This is a suggestion from experience, not a study guideline. If black coffee is too bitter for you, try a different roast or cold brew. Often it's not the coffee itself but a very dark roast. And if you find that giving up milk takes the fun out of fasting, a small eating window with a milky coffee at breakfast is still a perfectly sensible solution.
Can coffee harm your stomach while fasting?
It can cause discomfort if you're sensitive. Coffee stimulates stomach acid. On an empty stomach, that leads to heartburn, nausea or stomach pressure in some people. On top of that, caffeine suppresses appetite, so you may end up eating too little when your eating window begins.
This helps in practice:
- Start with a glass of water before the coffee.
- Choose mild, low-acid roasts or cold brew.
- Drink slowly and no more than two cups before your first meal.
- If you get heartburn, read our article Eating With Heartburn.
If you notice coffee doesn't agree with you while fasting, that's not a weakness. Then you simply drink it in your eating window.
What can I drink instead of coffee while fasting?
Water, unsweetened herbal tea and thin vegetable broth. The AOK recommends drinking at least two litres during the fasting phases. Tea is the easiest alternative because it keeps the ritual feel of a cup in your hand. You'll find our overview in the article Tea for Fasting.
If you miss the flavour: the Happy Stomach Tea with linden blossom, aniseed, fennel, chamomile, ginger and sage is mild and also suits a nervous stomach. If you're looking for caffeine without drinking coffee, our page on organic teas has a selection, including a green tea with guarana.
You're better off skipping energy drinks and diet sodas. Sweeteners are low in calories, but in some people they stimulate appetite.
When should you skip coffee while fasting?
Lower limits apply during pregnancy: the EFSA recommends a maximum of 200 mg of caffeine per day here. Pregnant and breastfeeding women shouldn't fast anyway. The AOK also lists people with low blood pressure or metabolic conditions, older people and people with pre-existing conditions, people with eating disorders and cancer patients in active treatment as groups who should avoid intermittent fasting. If you take blood thinners or antidepressants, you should ask your doctor first.
If you have heart rhythm disorders, anxiety disorders or sleep problems, also ask a doctor first. Caffeine can increase palpitations and inner restlessness, especially if you're already taking in less energy because of fasting.
On a Juice Cleanse, coffee isn't ideal either; we explain why in the article Coffee, Nicotine and Alcohol on a Juice Cleanse.
Pairs well with frank.
If you'd like to start intermittent fasting with a clear plan, you'll find suitable products in our collection 5:2 Intermittent Fasting There are also juices there that you can plan in as a meal on your calorie days.
You might also like
- What Is Intermittent Fasting and What Are the Rules?
- Tea for Fasting
- Coffee, Nicotine and Alcohol - Things to Avoid During a Juice Cleanse
Frequently asked questions about coffee while fasting
Does coffee with milk break intermittent fasting?
Yes, strictly speaking it does. Milk provides calories and carbohydrates. A small splash changes little about ketosis, but you're then no longer fasting in the strict sense.
How many cups of coffee are okay while fasting?
For healthy adults, up to 400 mg of caffeine per day is considered safe. That's roughly four cups. One to two cups before your first meal make sense.
Does coffee with sweetener break the fast?
Sweeteners have hardly any calories, but in some people they can stimulate appetite. If you're unsure, leave them out during the fasting phase.
Is coffee allowed on therapeutic fasting or a Juice Cleanse?
On therapeutic fasting and Juice Cleanses, people usually go without it or cut the amount right back. Water and herbal tea take centre stage there.
Does coffee cause cravings while fasting?
In some people yes, in others it suppresses hunger. The effect is individual. Drink water alongside it and watch how you react.
Note: This article is for general information and does not replace medical or therapeutic advice. If you have symptoms or pre-existing conditions, are pregnant or take medication, please speak to your doctor first.
