Can You Have Fluids During Intermittent Fasting?

December 29, 2025 •

4 min read

While it may seem counterintuitive, staying hydrated is one of the most critical elements of a successful intermittent fasting regimen. Yes, you can and should have fluids during intermittent fasting, but the key is knowing which ones are safe to consume without breaking your fast. This guide will clarify the do's and don'ts of drinking while fasting.

Quick Summary

This guide explains which fluids are permitted during intermittent fasting to maintain hydration and fasting benefits. It details safe zero-calorie options like water, black coffee, and herbal tea, while outlining beverages to avoid that would break your fast. Learn how to stay properly hydrated and manage hunger.

Key Points

Water is your priority: The most important fluid during a fast is plain, unsweetened water for essential hydration.
Stick to zero calories: Drinks like black coffee and herbal tea are acceptable as long as they contain no sugar, milk, or other caloric additives.
Avoid caloric beverages: Juices, sodas (including diet), alcohol, and milk-based drinks will break your fast and should be avoided.
Replenish electrolytes: To prevent fatigue and headaches, especially during longer fasts, consider adding a pinch of salt or a zero-calorie electrolyte supplement to your water.
ACV is fast-friendly in moderation: A small, diluted amount of apple cider vinegar can be consumed to help with cravings without breaking the fast.
Stay aware of your body: Pay attention to signs of dehydration, like headaches or dizziness, and increase your fluid intake accordingly.

Hydration Is Essential for Fasting Success

Proper hydration is not just allowed during an intermittent fast—it's essential. When you fast, your body loses water and electrolytes more quickly than usual, primarily because of a drop in insulin levels. As insulin decreases, the kidneys excrete more sodium and water, a natural diuretic effect. This can lead to dehydration and electrolyte imbalance, causing side effects like headaches, dizziness, and fatigue. Maintaining your fluid intake helps manage these symptoms and supports the metabolic processes that make fasting beneficial.

Safe Fluids That Won't Break Your Fast

To maintain a fasted state, you must consume fluids that contain zero or a negligible amount of calories. Anything that triggers an insulin response will break the fast, so avoiding sugar and artificial sweeteners is key.

Plain Water: The number one fluid for fasting is water. Tap, filtered, and mineral water are all excellent choices. It keeps you hydrated and can help manage hunger pangs by creating a feeling of fullness.
Black Coffee: Black coffee contains minimal calories and will not break your fast. Many people find that the caffeine helps suppress appetite and provides an energy boost during fasting hours. However, avoid adding milk, cream, sugar, or flavored syrups.
Plain Tea (Herbal and Caffeinated): Unsweetened herbal, green, and black teas are also fast-friendly. They are virtually calorie-free and provide hydration. Like black coffee, be sure to drink them without added sugars or milk.
Sparkling Water: For a change of pace from still water, carbonated or sparkling water is a safe option, as it contains no calories. Be mindful of flavored options, as some may contain sweeteners. Stick to plain versions to be safe.
Diluted Apple Cider Vinegar (ACV): Some people find that a small amount of apple cider vinegar (1–2 teaspoons) diluted in a large glass of water can help with cravings. With only trace calories, it's unlikely to break a fast when used in moderation.

Why Electrolytes are Crucial During Fasting

As your body loses water and sodium during fasting, replenishing electrolytes becomes important, especially during longer fasts or if you're physically active. An imbalance of electrolytes can lead to headaches, fatigue, and muscle cramps.

Himalayan Pink Salt: Adding a small pinch of high-quality salt to your water can help replenish lost sodium and other trace minerals.
Zero-Calorie Electrolyte Supplements: For those needing a more balanced boost, sugar-free electrolyte powders are available. Read labels carefully to ensure no added sugars or artificial sweeteners that could trigger an insulin response.
Bone Broth: While containing some calories, some who practice "dirty fasting" allow a cup of bone broth. It provides valuable electrolytes and nutrients with minimal caloric impact, which can help in longer fasts.

Fluids to Avoid During Intermittent Fasting

Any fluid with significant calories, carbohydrates, or protein should be avoided as it will break your fast. This includes:

Soda (Diet and Regular): Both regular soda and diet sodas can be problematic. Regular soda is full of sugar and calories. While diet sodas are calorie-free, some artificial sweeteners can still trigger an insulin response or negatively affect gut bacteria.
Juice and Smoothies: Fruit and vegetable juices are high in sugar, which will immediately break your fast. Smoothies, even green ones, contain calories and should be saved for your eating window.
Milk and Cream: Adding milk, cream, or other dairy products to your coffee or tea will add calories and protein, thus breaking the fast.
Alcohol: All alcoholic beverages are caloric and will instantly break a fast. Additionally, alcohol can dehydrate you, which is counterproductive during fasting.

Fast-Friendly vs. Fast-Breaking Drinks


Drink Type	Fast-Friendly (Minimal Calories)	Fast-Breaking (Significant Calories/Additives)
Water	Plain, sparkling, mineral	Flavored or sweetened water
Coffee	Black, plain, unsweetened	With milk, cream, sugar, syrup
Tea	Herbal (plain), Green, Black	With milk, sugar, honey, fruit juice
Electrolytes	Zero-calorie electrolyte powder, Pinch of salt	Sugary sports drinks, flavored electrolyte mixes
Vinegar	Diluted Apple Cider Vinegar (1-2 tsp)	Sweetened ACV gummies or drinks
Broth	Plain bone broth (for "dirty" fasts)	Vegetable broths with starches or beans

Staying Hydrated to Overcome Fasting Side Effects

As your body adjusts to intermittent fasting, you might experience headaches, fatigue, or dizziness. Proper hydration with the right fluids is the best way to combat these symptoms. If you are feeling unwell, it's a good indicator that you need to increase your fluid intake, possibly with added electrolytes. Listen to your body and prioritize hydration. The goal is to make fasting a sustainable practice, and managing side effects through smart fluid choices is a key part of that.

Conclusion

In summary, the answer to "can you have fluids during intermittent fasting?" is a resounding yes, as long as they are calorie-free. Water is your best friend, while unsweetened coffee and tea are also safe options that can help suppress appetite and provide energy. Prioritizing hydration and being mindful of which fluids to avoid are essential for a successful and comfortable fasting experience, helping you maximize the benefits without breaking your fast. Consult with a healthcare professional before beginning any new diet or fasting protocol to ensure it's right for you.

Visit Healthline for more detailed information on which drinks are safe during a fast.

Frequently Asked Questions

No, plain black coffee contains a negligible number of calories and will not break your fast. You must avoid adding milk, cream, sugar, or any sweeteners, as these would add calories and trigger an insulin response.

It is best to avoid diet soda during a fast. While calorie-free, some artificial sweeteners have been shown to potentially trigger an insulin response or disrupt gut bacteria, which can interfere with the metabolic goals of fasting.

Yes, lemon-infused water is generally safe, as the amount of calories from a few lemon slices is insignificant and will not break your fast. However, avoid adding too much lemon juice, which could add up to more calories.

Bone broth contains some calories and is typically not allowed during a strict fast. However, some who practice a 'dirty fast' may consume it, especially during longer fasts, to replenish electrolytes and nutrients with minimal caloric impact.

Any addition of milk or cream, even a small splash, adds calories and protein that will break your fast. For best results, stick to plain black coffee or tea.

Plain, unsweetened herbal teas are completely fine and can be a great way to stay hydrated and warm during a fast. Just ensure there is no added sugar or sweetener.

Zero-calorie electrolyte supplements or adding a pinch of salt to your water will not break a fast. Replenishing electrolytes is important, particularly for longer fasts, and these options help maintain your fast while preventing side effects like dizziness and fatigue.