Is there anything I can put in my coffee that won't break a fast?

October 3, 2025 •

4 min read

A standard 8 oz cup of black coffee contains only about 3 calories, and since it has no fat, protein, or sugar, it will not disrupt a fast. However, figuring out what you can put in your coffee that won't break a fast requires understanding the impact different ingredients have on your metabolism.

Quick Summary

This guide explains which coffee additives are safe during a fast, distinguishing between zero-calorie options like spices and specific sweeteners, and low-calorie fats. It clarifies why traditional creamers and sugars should be avoided, helping individuals adhere to their intermittent fasting protocols.

Key Points

Black Coffee is the Safest Bet: For a pure, zero-calorie fast, plain black coffee is the only additive-free option that won't break your fast.
Zero-Calorie Sweeteners Are Generally OK: Natural sweeteners like Stevia, Monk Fruit, and Erythritol do not contain calories and typically don't trigger an insulin response.
Spices Enhance Flavor Without Calories: A dash of cinnamon, nutmeg, or unsweetened cocoa powder can flavor your coffee without disrupting your fast.
Fats are a Gray Area: Adding fats like MCT oil or heavy cream is common for keto fasting, but it technically adds calories and will break a strict, zero-calorie fast aimed at autophagy.
Avoid All Sugars and Conventional Creamers: Any form of sugar, dairy milk, or sweetened creamer will add calories and carbohydrates, definitively breaking your fast.
Consider your Fasting Goals: Your choice of additive should align with your specific fasting objectives, such as metabolic health, weight loss, or maximum autophagy.

Understanding What Breaks a Fast

For those practicing intermittent fasting, the core principle is to maintain a state where the body is not processing calories and can continue to draw energy from stored fat. Technically, any caloric intake will break a fast. However, most intermittent fasting protocols focus on avoiding any significant insulin response, which is primarily triggered by carbohydrates and, to a lesser extent, protein. A small amount of calories, especially from fat, is often considered acceptable by many fasters, though purists prefer zero-calorie drinks only. The key is to understand the impact of different substances on your blood sugar and insulin levels.

The Safest Option: Black Coffee

The most straightforward answer to the question 'Is there anything I can put in my coffee that won't break a fast?' is nothing at all. Black coffee is the best and safest option. Whether you prefer drip coffee, espresso, or cold brew, as long as it's plain and unsweetened, it is perfectly fine during a fasting window. Black coffee has been shown to have multiple benefits during a fast, including appetite suppression and enhanced fat-burning. For those who find black coffee too bitter, a pinch of pink Himalayan salt can help neutralize the bitterness.

Minimal Impact Additives

For those who need a bit more flavor, there are some minimal-calorie options that are unlikely to significantly impact your fast, especially if your primary goal is weight loss or metabolic health rather than strict autophagy.

Zero-Calorie Sweeteners

Natural zero-calorie sweeteners are a popular choice. Extracts like Stevia and Monk Fruit are often used because they provide sweetness without any calories or carbohydrates that would trigger an insulin spike. Erythritol is another sugar alcohol that is generally considered fast-safe and has a glycemic index of zero. However, some studies suggest that artificial sweeteners can still impact gut bacteria or potentially trigger cravings, so they should be used in moderation.

Spices and Flavorings

A small sprinkle of certain spices can enhance the flavor of your coffee without adding calories. Some excellent options include:

Cinnamon: Adds a warm, sweet flavor and may even help with blood sugar control.
Nutmeg: A hint of nutmeg provides a nutty, aromatic touch.
Unsweetened Cocoa Powder: In small amounts (less than a tablespoon), it adds a rich, chocolatey flavor with minimal caloric impact.
Vanilla Powder or Extract: Use pure vanilla extract or powder for flavor without added sugar.

Should You Add Fat to Your Coffee?

The practice of adding fat to coffee, often referred to as 'Bulletproof Coffee,' is popular in ketogenic and low-carb diets. Additives like MCT oil, coconut oil, or a small splash of heavy cream can be used. Proponents argue that since fat doesn't raise insulin levels, it won't break a fast focused on ketosis. The fat can provide a source of energy and help with satiety, potentially extending the fasting window.

However, it is crucial to note that adding fat will introduce calories and technically break a strict fast, especially if the goal is autophagy, the process of cellular cleansing that is maximized in the absence of calories. A very small amount of heavy cream (e.g., less than a tablespoon) is often considered a compromise by some.

Additives to Avoid

To ensure you don't inadvertently break your fast, steer clear of common coffee additives that contain calories, sugar, or carbohydrates. This includes:

Sugar and honey
Standard milk (skim, 2%, whole)
Sweetened creamers (both dairy and non-dairy)
Most non-dairy milks (almond, oat, soy) because of their carbohydrate content
Syrups and flavored packets

Coffee Additive Comparison Table


Additive	Caloric Impact	Insulin Response	Fasting Protocol	Notes
Black Coffee	Almost zero	Negligible	Safe for all types	Provides caffeine without breaking fast.
Stevia/Monk Fruit	Zero	Negligible	Safe for most	May trigger cravings in some.
Erythritol	Zero	Zero	Safe for most	Generally considered safe, zero glycemic index.
Cinnamon	Minimal	Negligible	Safe for all types	Adds flavor and may aid blood sugar.
Heavy Cream (small)	Low	Low	OK for metabolic	Technically breaks a strict fast, but minimal impact.
MCT Oil/Butter	Moderate	Low	OK for keto	Provides fat-based energy, breaks strict autophagy fast.
Standard Milk/Sugar	High	High	Not suitable	Will definitely break your fast.
Oat Milk	Moderate	Moderate	Not suitable	Contains carbohydrates and calories.

Conclusion

Ultimately, whether a coffee additive breaks a fast depends on your specific fasting goals. For a strict, zero-calorie fast intended to maximize autophagy, plain black coffee is the only safe option. For those prioritizing ketosis or weight management, small amounts of low-carb fats like MCT oil or heavy cream might be acceptable to increase satiety without causing a significant insulin spike. If you simply need a flavor boost, zero-calorie sweeteners like Stevia and Monk Fruit or a dash of spices like cinnamon are excellent alternatives. Experiment with what works best for your body and your fasting regimen, keeping in mind that any added calories, however minimal, will technically end the fasted state. To learn more about the science behind intermittent fasting, you can consult research like this study from the Journal of Translational Medicine.

Frequently Asked Questions

No, a small pinch of pink Himalayan salt will not break a fast. It is a calorie-free mineral and is sometimes added to coffee to counteract bitterness, enhancing the flavor without affecting your fasted state.

Yes, you can. As long as the coffee is flavored naturally during the roasting process with no added sugars or syrups afterward, it is considered safe for fasting and won't add calories to your brew.

Yes, unsweetened and additive-free cold brew coffee is a fasting-safe option. Its naturally smoother and less acidic taste can be more palatable for those who dislike black hot coffee.

While zero-calorie sweeteners like Stevia and Monk Fruit are generally considered safe, there is some debate. Some studies suggest that the sweet taste could still cause an insulin response in certain individuals, so usage should be conservative.

Most non-dairy milks contain carbohydrates and calories, and even unsweetened varieties can be enough to break a fast. It is best to avoid them during your fasting window, especially for strict protocols.

A tiny splash (less than a tablespoon) of heavy cream is low in carbs and is sometimes used by those with weight loss goals, though it does contain calories and technically breaks a strict fast. It is not recommended for those prioritizing autophagy.

Yes, decaf coffee is also a safe choice during fasting, as it contains a negligible amount of calories. It is a great option for those who are sensitive to caffeine but still enjoy the taste of coffee.