Can You Drink Coffee While Fasting? (Intermittent Fasting Explained)
Fasting—especially intermittent fasting (IF)—has become increasingly popular for weight management, metabolic health, and mental clarity. But one question comes up again and again:
Can you drink coffee while fasting?
The short answer is yes, in most cases—but how you drink your coffee matters. In this guide, we’ll explain when coffee is allowed during fasting, what breaks a fast, and how to enjoy coffee without compromising your fasting goals.
What Counts as Fasting?
Fasting generally means avoiding calories for a specific period of time. The most common types include:
- Intermittent fasting (16:8, 18:6, OMAD)
- Extended fasting (24+ hours)
- Religious or traditional fasts
- Metabolic fasting (focused on insulin response)
For most people practicing intermittent fasting, the goal is to keep insulin low, allow the body to burn stored fat, and avoid triggering digestion.
Does Coffee Break a Fast?
Black Coffee: Usually Safe
Plain black coffee does not break a fast for most fasting methods.
Black coffee contains:
- ~0–5 calories per cup
- No sugar
- No carbohydrates
- No protein or fat
Because it has a negligible calorie impact and does not significantly raise insulin levels, black coffee is generally considered fast-friendly.
What Kind of Coffee Is Allowed While Fasting?
Allowed During a Fast
- Black coffee (hot or iced)
- Espresso
- Americano
- Cold brew (unsweetened)
What Typically Breaks a Fast
- Sugar, honey, maple syrup
- Milk, cream, oat milk, almond milk
- Flavoured syrups
- Protein powder
- Butter or MCT oil (technically breaks a fast, but see below)
What About Bulletproof Coffee?
Bulletproof coffee (coffee with butter or MCT oil) technically breaks a fast because it contains calories and fat.
However:
- It may still keep insulin low
- Some people use it for fat-adaptation or ketogenic fasting
- It’s not considered a clean fast
If your goal is:
- Weight loss or metabolic fasting → avoid it
- Ketosis or mental performance → it may be acceptable
Can Coffee Help With Fasting?
Yes—coffee can actually support fasting when consumed correctly.
Potential Benefits
- Suppresses appetite
- Increases alertness and focus
- May enhance fat oxidation
- Makes fasting easier to maintain
That said, excessive caffeine can increase stress hormones in some people, especially on an empty stomach.
Best Coffee Tips While Fasting
To get the benefits without side effects:
- Drink high-quality coffee
- Avoid added sweeteners
- Stay hydrated (drink water too)
- Limit intake if you feel jittery or anxious
- Stop if you experience stomach irritation
If you’re looking for clean, flavourful options, explore our curated selection of Canadian-sourced beans in our specialty coffee collection —perfect for enjoying black without bitterness.
Does Coffee Affect Autophagy?
Autophagy (cellular cleanup) is a common fasting goal.
Current research suggests:
- Black coffee does not stop autophagy
- Polyphenols in coffee may actually support it
- Additives (milk, sugar) likely interfere
If autophagy is your primary goal, black coffee only is your safest choice.
Who Should Be Careful Drinking Coffee While Fasting?
You may want to limit or avoid coffee while fasting if you:
- Have acid reflux or gastritis
- Are sensitive to caffeine
- Experience dizziness or nausea
- Are pregnant or advised otherwise by a healthcare professional
Listen to your body—fasting should not feel punishing.
Final Verdict: Can You Drink Coffee While Fasting?
Yes—black coffee is generally allowed while fasting.
- It won’t break a clean fast
- It can make fasting easier
- It may offer metabolic benefits
Just keep it plain, unsweetened, and moderate.