Does coffee break a fast: to drink or not to drink?

Written by Aly Owen

Medically reviewed by Louise Bula, RD

Published on October 3, 2023 | Updated on June 17, 2024

Whether it’s the best part of waking up, a cozy afternoon refresher, or an after-dinner digestif, coffee is one of the most widely consumed beverages around the world — and its potent brew of caffeine, antioxidants, and other bioactive compounds makes a pretty compelling case for a range of health benefits, too.[1]   

So, it’s no wonder that we get a lot of questions about coffee and fasting: 

• Does coffee break a fast?
• Does black coffee break a fast? 
• Can you have coffee when fasting?
• Is black coffee okay for fasting?
• Where can I get a drip feed of the stuff? 

(Okay, in all fairness, that last one hasn’t really come up. But imagine if Emergen-C(offee) IVs existed …)

Whether you dabble in the occasional artisan blend or you’re an absolute fiend for the beans, the good news is that you don’t have to give up coffee during fasting windows, and that cup of joe may actually complement your intermittent fasting goals. You just need to be mindful of what you put in it and how much you have. 

Intermittent fasting and coffee: an overview

From simple pleasure to self-care to necessary fuel, coffee may be a big part of your daily comforts, and your well-being will always outweigh any caloric cons. 

Thankfully, doctors and dietitians agree that drinking coffee when fasting doesn’t actually pose many cons for the majority of people as long as you’re mindful of your approach — and it may even have some benefits, too. Coffee + fasting choices should also not involve lots of mix-ins or drinking so much that you disturb your sleep or irritate your digestive system.[3]

Especially if you’re still getting to grips with intermittent fasting for beginners, it can be difficult to know what you can drink while fasting, what breaks a fast, and how to manage it all. That’s where we come in. 

If you’ve been cleared to try intermittent fasting (primary care provider approval should always be step one), you can take our Simple quiz to hack both your eating and fasting windows to maximize your results.  

Coffee won’t disrupt your fast

Does coffee break your fast? Not inherently. Coffee in and of itself won’t disrupt your fast, so black coffee is okay for fasting.  

But will coffee break a fast? It depends on how you take it. You can drink coffee during a fast as long as you avoid additives high in calories (anything more than 10 calories).

Calories

Why doesn’t coffee break fast? A cup of black coffee contains 3–5 calories and minimal amounts of fat, protein, and minerals. Having less than 10 calories won’t knock your body out of its fasting state. 

Caffeine

A cup of coffee also contains 80–100 mg of caffeine. Up to 400 mg of caffeine a day is usually safe for most people,[4] but does caffeine break a fast? Within the safety bounds, caffeine doesn’t negatively impact your fast, and it may help prevent drowsiness during a fasting window. You just want to be wary of having too much, which can contribute to intermittent fasting mistakes like not getting enough sleep. 

Creamers and sweeteners 

So, when does coffee break intermittent fasting? 

While fasting, black coffee may not run interference, but you start channeling Johnny Cash and walking the line when you add sweeteners and creamers. Sugar and the proteins in milk, half and half, or cream contain calories that spike your blood glucose levels, which will trigger a break in your fast. 

Although artificial sweeteners avoid the influx of calories and are generally safe in moderation, more research is needed into their long-term effect on overall health,[5] especially with respect to glycemic impact and gut health.  

Coffee and intermittent fasting: shared benefits

The good news doesn’t stop with being able to drink coffee during fasting: fasting and coffee can actually work together to support certain health- and weight-related goals. 

Thanks to its caffeine and antioxidant compounds, coffee has been linked to a wide range of health benefits that have quite a bit of overlap with potential intermittent fasting benefits.[1]  

Psst! If you have a specific fasting goal and feel like you’re running into an intermittent fasting not working wall, we can help! Just tell us more about what you want to achieve through our Simple quiz, and we’ll give you some recommendations about switching things up with that in mind.

Weight / fat loss

If you’re intermittent fasting to lose weight, coffee may facilitate reductions in weight, BMI, and body fat.[6] One meta-analysis suggests these benefits may be more significant in men, but participants of all genders have experienced weight management benefits.[7] 

Ketosis

When you’re in ketosis — a fasted state about 12–16 hours after eating where your body is primed to burn fat instead of sugar — you’re using ketones as energy in lieu of glucose, and the caffeine in coffee may help you to stay on track during your fasting window.[8]

Brain health

Regular, light-to-moderate caffeine consumption via coffee may promote better alertness and cognitive function while reducing cognitive decline and the risk of depressive symptoms.[9,10,11] There’s some limited evidence that caffeine may even have a protective effect against dementia and Alzheimer’s in women,[10] but we still need more data to understand if, when, and how coffee might unlock these neurological benefits.

Insulin sensitivity

In the short term, caffeine may reduce insulin sensitivity,[12] but in the long run, it may actually improve glucose intolerance and insulin sensitivity.[13] Drinking coffee regularly has also been associated with a reduced risk of type 2 diabetes.[14] A word of warning, though: if you’re living with or at risk for any form of diabetes, you should always consult your doctor before modifying what you eat or drink. 

Metabolic health 

In addition to coffee’s potential benefits for insulin sensitivity, emerging research suggests it may be more broadly beneficial for improving metabolic health and reducing the risk of metabolic syndromes.[15,16] However, we still need more research, especially in different populations, to validate this concept further.

Inflammation

Coffee specifically — not just caffeine in the form of supplements! — has been linked to anti-inflammatory properties [17] and benefits that may reduce the risk of chronic diseases like cardiovascular disease.[18]

Autophagy 

Like ketosis, autophagy — a naturally occurring process that clears out damaged cells to make room for new ones — may be stimulated by fasting.[19] Whether or not caffeine can stimulate autophagy at this stage is still unknown, as most of the existing literature so far has been done using animal models.[20] There are still a lot of questions around how autophagy works, how it helps, and how we can use it.[21,22,23] 

Appetite

Some coffee drinkers swear cups of joe are crucial during fasting windows due to caffeine’s appetite-suppressing properties.[24] But it’s worth noting that the literature shows it only impacts appetite across a short period of time after ingesting coffee 0.5–4 hours before a meal. Whether or not it works for you in a safe, sustainable way may be related to your genes, the way you metabolize caffeine, and how you feel about bitter tastes.[24] 

Anti-aging

Both the caffeine and the antioxidants in coffee have been associated with healthy aging in certain contexts — like with respect to reducing the risk of all-cause mortality, including cardiovascular disease,[25] as well as improved physical functioning in older people [26] — but a lot more research is needed before we can confidently say if and how coffee may have anti-aging properties.  

Coffee while intermittent fasting: the risks 

Combining black coffee and fasting poses very few risks to your fasting process, but drinking coffee while fasting — even if coffee does “count” as a fasting-safe beverage — may still place some hurdles in your path if you overdo it on the caffeine. 

Caffeine and sleep disturbance 

You know that feeling of being wide awake, heart pounding, late at night as you listen to every little creak of the house after you watch a horror film? Or just, you know, have casual flashbacks to cringey moments from your past? 

Too much caffeine can lead to similar jumpy circumstances. Although sleep disturbances are one of the common initial intermittent fasting side effects, intermittent fasting has been shown to potentially improve sleep quality in some people,[27] and thus, caffeine can interfere with that — especially if you drink it late in the afternoon or evening. Good sleep is crucial for mood and cognitive functioning as well as mental, cardiovascular, and metabolic health, and poor sleep could also lead to weight gain.[28,29] 

Caffeine on an empty stomach

There’s a reason why your morning coffee is often the precursor to some quality time in the bathroom: caffeine and the compounds in coffee are like an acid bomb to your stomach,[30] and it can be especially irritating if you have inflammatory bowel disease, irritable bowel syndrome, or acid reflux disease. 

If you must drink coffee during a fast: dos & don’ts 

If the answer to “Does fasting include coffee?” has to be a resounding “YES!” for you (and/or your ability to function), rest assured, coffee isn’t something you need to give up for intermittent fasting. You may just need to make some substitutions or switch up how you take your coffee to avoid breaking your fast with calories.

Dos

Limit cream to tiny splashes 

Black coffee while fasting is best, but if you can’t live without a little hit of something extra, a tiny splash of cream is okay, and it won’t change how much fat you’re burning. 

Swap out sugar 

If black coffee fasting is way too bitter for you, switch out sugar for either artificial, sugar-free sweeteners (like Stevia or Splenda) or a tiny bit of natural flavor, like ginger or unsweetened cocoa powder. Cinnamon might be an ideal choice for coffee fasting, and it may even improve insulin sensitivity in people with type 2 diabetes without adding calories.[31]

Make your coffee at home

Coffee shops tend to use a “cream” that’s really a mix of milk and cream, which means even a tiny splash may contain more protein and carbs than you bargained for and break your fast. There’s also more of a risk of hidden sugar, like in the form of soy, rice, and nut milk (like almond milk) alternatives. 

Try cold brew or decaf 

If you’re managing a sensitive stomach, cold brews are generally less acidic, so they may be less irritating. If you’re concerned about your caffeine intake, you won’t necessarily miss out on potential coffee benefits if you switch to decaf.[32]

Don’ts

Have more than a few caffeinated cups

Coffee can absolutely be a comfort during fasting windows, but you don’t want it to become a crutch since too much caffeine can be a detriment not only to your fasting experience but also to your overall health.[4] Likewise, you want to keep calories below 10 to avoid breaking your fast.  

Drink caffeinated coffee after ~4 p.m. 

To avoid disrupting your sleep,[33] switch to decaf or stop drinking coffee six hours before your bedtime. If you’re extra sensitive to caffeine, make the switch even earlier. 

Forget to hydrate

A cup of coffee may have water in it, but it’s not a substitute for actual H₂O. Especially if you drink fully caffeinated coffee, staying hydrated is super important.[34] 

Compromise your enjoyment 

If all of these changes sound like a tall order — and one you really don’t want — remember: it’s never worth forcing yourself to consume things you don’t like just because they might lead to more benefits. If you prefer to take your coffee with extra hits of sugar and fat, try structuring your eating window to overlap with your mornings or prime coffee-drinking hours so you don’t have to worry about your coffee interfering with your fast. 

Written by Aly Owen

Medically reviewed by Louise Bula, RD

Published on | Updated on June 17, 2024