Is Cold Brew Ok for Intermittent Fasting? The Definitive Guide

October 19, 2025 •

4 min read

According to nutrition experts, black coffee is largely considered a fasting-friendly beverage, and this extends to cold brew, provided no high-calorie additives are used. So, is cold brew ok for intermittent fasting? The short answer is yes, but only when consumed black and unsweetened. This guide explores the specifics of why and how cold brew fits into a successful intermittent fasting routine.

Quick Summary

Pure, unsweetened cold brew coffee is acceptable for intermittent fasting as its negligible calorie count does not break a fast. This beverage can also help with appetite suppression and metabolic benefits, but any added sugar, milk, or cream will negate its fasting-friendly status.

Key Points

Acceptable When Black: Plain, unsweetened cold brew is acceptable for intermittent fasting as its near-zero calories won't break your fast.
Avoid Additives: Adding sugar, milk, cream, or syrups will introduce calories and trigger an insulin response, effectively ending your fast.
Less Acidic, Gentler on Stomach: The cold brewing process results in a smoother, less acidic coffee, which is often easier to drink black and better for sensitive stomachs.
Potential for Higher Caffeine: Be aware that cold brew can have a higher caffeine content than regular coffee, which could cause jitters for sensitive individuals, especially on an empty stomach.
Check Commercial Labels: If you buy bottled cold brew, always read the nutrition label to ensure it contains no added sugars or calories that could compromise your fast.
Potential Metabolic Boost: The caffeine in black cold brew can help suppress appetite and increase fat-burning, complementing your fasting goals.

The Core Principle of Fasting and Calories

Intermittent fasting relies on a simple rule: consuming zero or very few calories during your fasting window to keep insulin levels low. When you consume calories, particularly from sugar or carbohydrates, your body releases insulin to regulate blood sugar. This insulin release effectively ends your fasted state, shifting your body from a state of fat-burning (ketosis and lipolysis) and cellular repair (autophagy) back to a state of energy consumption from food.

Black coffee, including cold brew, contains a minimal amount of calories—typically under 5 calories per cup. This tiny caloric intake is generally not enough to trigger an insulin response and thus, does not break your fast for most people. The key is to consume it without any additions that would significantly raise its calorie count.

Why Cold Brew is a Great Fasting Companion

Cold brew is a fantastic option for intermittent fasting for several reasons beyond its low-calorie status. The unique brewing process, which involves steeping coffee grounds in cold water for an extended period, creates a smoother, less acidic, and naturally sweeter flavor profile compared to hot-brewed coffee.

Naturally Smoother Taste: The reduced acidity makes black cold brew more palatable for many individuals who typically need to add sugar or cream to hot coffee. This natural smoothness helps you stick to the 'black and unsweetened' rule with less effort.
Gentler on the Stomach: For those who experience stomach discomfort or acid reflux from hot coffee, cold brew is often a much milder alternative, allowing them to enjoy their caffeine fix without irritation.
Enhanced Metabolic Benefits: Like all black coffee, cold brew's caffeine content can stimulate your metabolism, increasing thermogenesis (heat production) and boosting fat oxidation. This can complement the fat-burning effects of intermittent fasting.
Appetite Suppression: Caffeine is a known appetite suppressant, which can be particularly helpful for managing hunger pangs during the longer fasting periods.

Potential Downsides and What to Watch For

While cold brew is generally fine for fasting, there are a few considerations to keep in mind:

Caffeine Content: Cold brew often has a higher caffeine content than regular coffee due to the brewing process and higher coffee-to-water ratio. This could be a problem for those sensitive to caffeine, potentially causing jitters or sleep disruption, especially when consumed on an empty stomach. Moderation is key, with experts often suggesting limiting intake to 3-4 cups per day.
Pre-made Products: Some commercially bottled or canned cold brew products contain added sugars, flavorings, or preservatives that will absolutely break a fast. Always read the nutrition label carefully to ensure there are no added ingredients and that the calorie count is negligible.
Individual Tolerance: A small number of individuals may be highly sensitive to any caloric intake, no matter how small, during a fast, especially those aiming for maximum autophagy. In such cases, water is the only truly 'clean' fasting beverage. However, for most people practicing time-restricted eating for weight management, black cold brew is perfectly acceptable.

A Simple Guide to Drinking Cold Brew While Fasting

Choose Plain Black Cold Brew: The simplest rule is to stick to pure cold brew made from just coffee grounds and water. Avoid all additions.
Check Labels for Pre-Bottled Options: If you purchase cold brew, verify the label for zero grams of sugar and zero or near-zero calories. Ingredients should list only coffee and water.
Heat it Up, If You Want: If you prefer a warm beverage, you can heat up your black cold brew concentrate. The cold-brewed flavor remains, but it offers the comfort of a hot drink.
Experiment with Brewing Time: If homemade, adjust the steep time. A longer steep can increase caffeine, while a shorter one can produce a milder flavor. Find what works for you.

Comparison of Fasting-Friendly Beverages


Beverage Category	Fasting Compatibility	Key Considerations
Black Cold Brew	Excellent (if pure)	Calorie-free, less acidic, potentially higher caffeine. Must be unsweetened.
Black Hot Coffee	Excellent (if pure)	Calorie-free. Standard option, but can be more acidic for some stomachs.
Water	Absolute (best choice)	100% calorie-free, essential for hydration. Plain or sparkling.
Unsweetened Tea	Excellent	Calorie-free, available in various flavors. Avoid herbal teas with added flavorings or sweeteners.
Flavored Syrups	Breaks Fast	Adds sugar and calories, triggering an insulin response.
Milk or Cream	Breaks Fast	Adds calories and sometimes sugars, which ends the fasted state.
Bulletproof Coffee	Debatable/Breaks Fast	Adds significant fat calories. While some keto-fasters use it, it disrupts the 'clean' fast for weight loss and autophagy.

Conclusion: Cold Brew and Intermittent Fasting Can Coexist

Ultimately, the question of "is cold brew ok for intermittent fasting" is best answered with a conditional "yes." For the majority of intermittent fasting practitioners, particularly those focused on weight management, a cup of plain, unsweetened cold brew is a perfect choice that will not break their fast. Its smooth, low-acid profile makes it an excellent alternative for those who find black coffee difficult to drink. However, strict fasters aiming for maximal autophagy may prefer to stick to water. Always be mindful of commercial brands, check ingredients carefully, and listen to your body's individual response to caffeine during your fasting window. For more in-depth information, you can explore resources on the science behind fasting and coffee Zero Longevity Science.

Frequently Asked Questions

Yes, adding any type of milk or milk alternative, including almond milk, will break your fast. Even a small amount contains calories and can cause an insulin response, negating the benefits of fasting.

This is a debated topic. While zero-calorie sweeteners don't contain energy, some purists believe that the sweet taste alone can trigger an insulin response. For a strict fast, it is best to avoid them, but for less strict approaches, a minimal amount may be acceptable. Listen to your body and its response.

As long as both are consumed black and unsweetened, they are both acceptable for intermittent fasting. The key difference is the brewing method and flavor profile, not the fasting compatibility.

For most people, drinking black coffee on an empty stomach is safe. However, some individuals may experience stomach upset, heartburn, or increased anxiety. If you experience negative side effects, try limiting your intake or switching to a less acidic variety.

Moderation is recommended. Limiting your intake to 3-4 cups per day is generally safe and helps avoid excessive caffeine consumption, which can disrupt sleep or cause jitters.

Bottled, flavored cold brews are almost always a no-go for fasting. They typically contain added sugars and calories from syrups, which will break your fast. Always check the nutrition label carefully.

Similar to zero-calorie sweeteners, sugar-free syrups contain artificial ingredients that can disrupt a 'clean' fast for some people. While they contain no calories, the taste can still potentially impact your body's hormonal state. For best results, stick to plain cold brew.