Coffee and Intermittent Fasting – How to Drink Coffee Without Breaking Your Fast?

Intermittent fasting is gaining popularity as a method to improve health and body composition. Many enthusiasts wonder if they can enjoy a cup of their favorite coffee during the fasting window without breaking their fast. Does caffeine disrupt the diet? Will a splash of milk or sugar ruin our efforts? In this article, we clear up doubts about coffee consumption during intermittent fasting. You’ll learn how to drink coffee without breaking your fast, the rules regarding additives (milk, sweeteners, MCT), and tips to enjoy your black coffee risk-free. At JAVA Coffee Roasters, we are passionate about coffee and a healthy lifestyle, and we’ll show you how mindful coffee drinking can perfectly complement intermittent fasting.

Table of Contents

• What is intermittent fasting and why does coffee raise doubts?
• Does black coffee break the fast? What research says
• Coffee additives and fasting: milk, sugar, sweeteners – to watch or avoid?
• Coffee during fasting – benefits and potential effects (energy, appetite, autophagy)
• How to drink coffee on an empty stomach during fasting? (practical tips)
• Frequently asked questions about coffee during intermittent fasting

What is intermittent fasting and why does coffee raise doubts?

Intermittent fasting (IF) is a dietary model alternating periods of eating and fasting. The most popular schedules are 16/8 (16 hours fasting and 8 hours eating window) and 5:2 (5 days normal eating and 2 days with heavily restricted calories). During fasting, the body should not receive calories to avoid disrupting processes like autophagy, insulin sensitivity, and fat burning.

• Autophagy is a natural “internal cleaning” process in cells – the body breaks down and removes damaged proteins, toxins, and old cell components. Autophagy helps cells regenerate, improving overall function. This process activates mainly during longer fasting periods.
• Insulin sensitivity refers to how effectively the body responds to insulin – the hormone that helps lower blood glucose levels. Good insulin sensitivity means fewer blood sugar spikes and a reduced risk of insulin resistance and type 2 diabetes. Eating too often or excessively can weaken this sensitivity – which is why intermittent fasting can help.
• Fat burning – during fasting, when no calories are consumed, the body must use stored energy. It switches from burning glucose (from food) to burning fat, drawing from fat tissue as fuel. This is one main reason many people use IF for weight loss.

So, what about coffee? Black coffee, consumed without sugar, milk, or other additives, contains almost zero calories and does not directly break the fast, which is why most experts consider it allowed during the fasting window. However, coffee is not just water; it also contains caffeine, which can affect cortisol and insulin levels and stimulate the digestive system. This raises doubts, especially among more advanced intermittent fasting practitioners who want to maintain a so-called clean fast. Additionally, some on this diet add milk, plant-based drinks, coconut oil, MCT, or butter to their coffee, which may break the fast depending on the goal (e.g., autophagy vs. appetite control).

Learn more about how long caffeine works in our comprehensive guide on the effects of coffee.

Does black coffee break the fast? What does research say?

Good news for all coffee lovers – black coffee practically does not break the fast. A cup of black coffee (without milk and sugar) contains less than 3 kcal and has no significant amounts of protein or carbohydrates [1]. This calorie amount is too low to trigger a significant bodily response – it should not inhibit metabolic processes during fasting (e.g., fat burning or autophagy). Studies show that moderate black coffee consumption during fasting does not affect blood sugar or insulin levels in most people [2]. Moreover, coffee can even help during fasting – caffeine slightly suppresses appetite and boosts energy, making it easier to last until the end of the fasting window [1].

Coffee additives and fasting: milk, sugar, sweeteners – caution or avoid?

When it comes to additives, things get complicated because what you add to your coffee can negate the effects of fasting.

• Milk and cream. Even a small amount of milk in coffee provides protein, sugar (lactose), and fat. A tablespoon of milk is about 5–10 kcal – theoretically small, but in sensitive individuals it triggers a minimal insulin response. If your fasting goal is autophagy and complete metabolic rest, it's better to avoid milk. However, a tablespoon of milk or low-fat plant milk likely won't significantly break intermittent fasting for weight loss – but it may inhibit autophagy. Therefore, during fasting, only black coffee is recommended.
• Sugar. This is straightforward – sugar is pure carbohydrates. Even one teaspoon (about 16 kcal) causes a spike in glucose and insulin, definitely breaking the fast. Therefore, no sugar, honey, or syrups in coffee during fasting windows. If you miss sweetness, consider sweeteners.
• Calorie-free sweeteners. A controversial topic. Sweeteners like stevia, erythritol, or sucralose have no calories, so technically they don't provide energy. Most studies indicate they don't cause significant insulin response and thus shouldn't break fasting calorically. However, in some people, the sweet taste (even without sugar) increases hunger or minimally disrupts fasting via neurological mechanisms. The takeaway? A small amount of sweetener likely won't affect fasting physiologically, but if you can – better drink coffee without these additives to avoid triggering the body with sweet taste.
• Butter, MCT oil (so-called bulletproof coffee). Coffee with clarified butter or MCT oil is popular in the keto community. However, it provides a lot of fat and about 100–200 kcal, which definitely breaks a traditional fast (calories are calories). Advocates argue that pure fat does not raise insulin like sugar – that’s true, but the body still stops being in fasting mode because it receives fuel. If your fasting goal is weight loss or metabolic improvement, bulletproof coffee during the fasting window is not recommended – better to drink it during the eating phase.

In summary, it is safest to drink black coffee. Small amounts of plant milk or sweetener won’t ruin the world, but may slightly affect the body – the choice is yours and depends on how strictly you treat fasting.

Also check out: Why you should drink coffee before training – 5 reasons

Coffee during fasting – benefits and potential effects (energy, appetite, autophagy)

Black coffee can actually be an ally during fasting. Caffeine adds energy when we don’t eat – this helps fight morning fatigue or lack of concentration. For many people, the ritual of drinking a warm cup of coffee in the morning helps them last until their noon meal, as it slightly tricks hunger (occupies the stomach and stimulates the satiety center) [1]. Moreover, studies suggest that coffee enhances certain beneficial fasting effects, e.g., stimulation of fat metabolism or even the process of autophagy (cellular self-cleaning) [3]. Coffee contains antioxidants that have anti-inflammatory effects – combined with fasting, which also positively affects inflammatory parameters, they form quite a good team. However, remember moderation – one or two cups during fasting are enough. Too much caffeine on an empty stomach will bring opposite effects.

Wondering if coffee is healthy? Read our next article.

Unfortunately, sensitive individuals drinking coffee on an empty stomach (because during the fasting window we are fasting) may experience stomach discomfort – heartburn, reflux, stomach pain. If you have such a problem, try low-acidity coffee, e.g., mild Arabica from Brazil, which is gentler. Solutions include limiting the dose or adding a bit of plant-based milk or milk to soften it, although this is a compromise described above. Finally, hydration is important – coffee slightly dehydrates, and during fasting, we don’t get fluids from food. Therefore, drink a glass of water with every coffee to maintain fluid balance.

Read more about coffee beans gentle on the stomach.

How to drink coffee on an empty stomach during fasting? (practical tips)

Intermittent fasting with coffee can be more enjoyable if well planned!

1. Choose high-quality coffee. Since you drink it without additives, the quality of the beans greatly impacts the taste. Freshly roasted specialty coffee (e.g., single origin from JAVA Coffee Roasters) is naturally sweet and balanced, making it easier to enjoy without milk or sugar.
2. Brew with alternative methods. If espresso on an empty stomach is too strong for you, try lighter methods like drip, Aeropress, or Chemex. They produce a clear, less oily coffee that is often gentler on the stomach. You can also prepare cold brew the day before and drink it chilled or at room temperature in the morning – it has lower acidity.
3. Drink slowly and listen to your body. Instead of gulping down espresso in one go, sip your black coffee slowly. Observe how you feel. When you experience pleasant stimulation, don’t immediately reach for a second cup. Too much caffeine can cause jitters, especially on an empty stomach.
4. Avoid coffee late during the fast. If your fast lasts until noon, try not to drink coffee just before it ends (e.g., at 11:50), as it may suppress appetite too much and make eating the first meal on time difficult. Better to drink coffee in the first half of the fasting window.
5. Experiment cautiously with zero-calorie additives. If you really miss “white coffee,” try adding a teaspoon of unsweetened plant drink. Check how it affects your well-being during fasting. For most people, this addition won’t break weight loss, but it depends individually. If your goal is autophagy and health benefits, better stick to pure black coffee.
6. Stay hydrated. Drink water along with your coffee. It’s a good habit to drink a glass of water right after waking up (before coffee) to rehydrate after the night. Coffee does not replace water and actually requires replenishment.

Also read: Coffee on an empty stomach or after breakfast – does the time of drinking coffee matter?

Frequently Asked Questions about Coffee During Intermittent Fasting

Can I add a little milk to my coffee during a 16/8 fast?

If you want a pure fast – better not. However, a small amount (e.g., 20–30 ml) of milk in morning coffee probably won’t ruin weight loss during a 16/8 diet since it’s still few calories. It may slightly inhibit some of the fast’s health processes (like autophagy). Choose unsweetened plant milk with lower calories. Remember not to exceed these amounts – lattes (with lots of milk) should be reserved for the eating window.

Does bulletproof coffee really not break the fast?

Unfortunately, that’s an internet myth. Bulletproof coffee provides a lot of fat and calories, so it breaks a classic fast. It’s true it doesn’t spike insulin like a carb meal, so some on keto use it instead of breakfast. But if we talk about intermittent fasting meaning no calories – such coffee ends the fast. You can use it as your first meal in a 16/8 scheme (i.e., not during the 16 hours fasting window but at the start of the 8 hours eating window).

Are sweeteners (e.g., stevia) allowed in coffee during fasting?

Yes, most zero-calorie sweeteners don’t provide calories or raise blood sugar, so they don’t break the fast. Stevia, erythritol, xylitol (in small amounts) are considered safe during fasting windows. Beware of large amounts, as erythritol in higher doses can have a laxative effect, which isn’t pleasant on an empty stomach. Also, some say sweet taste increases hunger. In summary, 1–2 stevia tablets in coffee probably won’t harm your fast.

When is the best time to drink coffee during a 16/8 fast – immediately in the morning or just before eating?

It’s individual. Many people drink coffee right after waking (e.g., at 7:00 AM), which helps them last the entire fasting period until their first meal at noon. Others prefer to drink coffee later in the morning to curb appetite just before the fast ends. Remember that drinking coffee very close to the first meal may cause satiety – if you struggle with appetite when opening your eating window, drink coffee earlier. Also, avoid drinking coffee too late in the afternoon as it may disrupt your circadian rhythm and make falling asleep harder (which indirectly negatively affects fasting benefits).

What coffee should I choose to drink black during fasting?

The tastier the coffee, the easier it is to drink it without additives. We recommend specialty-grade beans – they provide a naturally sweet and rich brew. Great choices are single origin coffees with notes of chocolate, nuts, or fruits from the JAVA Coffee Roasters range. They have a full flavor that doesn’t need milk or sugar. If you prefer espresso, choose beans with low acidity and balanced profiles. With good-quality beans, black coffee becomes a pleasure even on an empty stomach.

Also read: Arabica vs Robusta – what are the differences and which coffee to choose?

Sources

1. Healthline, Can You Drink Coffee While Doing Intermittent Fasting?, accessed: 09.06.2025.
2. Zero Longevity Science, Does Coffee Break Your Fast?, accessed: 09.06.2025.
3. Stephen Anton PhD, Coffee and Autophagy: A Powerful Combination for Our Metabolism, accessed: 09.06.2025.
4. Johns Hopkins Medicine, Intermittent Fasting: How does it work?, accessed: 09.06.2025.