Is it okay to drink liquids while fasting?

October 31, 2025 •

4 min read

According to Healthline, drinking water during an intermittent fast is usually acceptable and even recommended. However, the answer to 'Is it okay to drink liquids while fasting?' depends heavily on the specific type of fast you are observing and the liquid itself.

Quick Summary

Consuming zero-calorie liquids like water, black coffee, and unsweetened tea is generally permissible during intermittent fasting to maintain hydration. Caloric beverages will break the fast, while dry fasting prohibits all liquids. The specific rules depend on your fasting type and goals.

Key Points

Zero-Calorie Liquids are Key: For intermittent fasting, only non-caloric liquids like water, black coffee, and unsweetened tea are allowed.
Dry Fasting is the Exception: This method prohibits all liquids, including water, for a set period.
Electrolytes are Crucial for Extended Fasts: For fasts lasting over 24 hours, supplementing with zero-calorie electrolytes helps prevent deficiency symptoms like fatigue and headaches.
Caloric Drinks Break a Fast: Beverages containing calories, including juices, sodas, and milky coffees, will end your fasting state.
Prioritize Hydration: Drinking plenty of water is essential during fasting to maintain bodily functions, manage hunger, and prevent dehydration.
Medical Instructions Take Precedence: Always follow a healthcare provider's specific instructions when fasting for a blood test or medical procedure.

Fasting has many forms, ranging from intermittent schedules to religious practices and pre-medical procedures, and liquid rules vary significantly for each. For most modern fasts focused on metabolic benefits like those found in intermittent fasting (IF), maintaining hydration with zero-calorie liquids is not only allowed but essential. Staying properly hydrated helps prevent headaches, fatigue, and muscle cramps that can be common side effects of fasting.

The Core Rules of Liquid Consumption While Fasting

For the majority of popular fasting methods like the 16:8 or 5:2 diet, the primary rule is simple: if it contains calories, it breaks the fast. The goal of these fasts is to keep insulin levels low, and consuming calories triggers an insulin response. This rule, however, changes completely for a dry fast, which restricts all food and liquids, including water. Similarly, if you are fasting for a medical procedure, a healthcare professional's instructions supersede all general advice.

What You Can Drink

For intermittent fasting, a range of zero-calorie options are available to help you stay hydrated and curb hunger.

Plain Water: The best and most fundamental option for hydration. Both still and sparkling water are acceptable, provided they have no calories.
Black Coffee: Contains minimal calories and offers a metabolism boost and appetite suppression. It must be consumed without sugar, milk, or cream.
Unsweetened Tea: Green tea and herbal teas are excellent zero-calorie choices. They offer antioxidants and can be calming. Ensure they are unsweetened and without milk.
Infused Water: Adding slices of lemon, cucumber, or mint to water can add flavor without calories, making it more enjoyable to drink.
Diluted Apple Cider Vinegar: Mixing a small amount of ACV with water can help with cravings, but some people find it harsh on an empty stomach.

Hydration, Electrolytes, and Avoiding Dehydration

Proper hydration during a fast is critical for maintaining metabolic function and overall well-being. The body loses water and electrolytes more rapidly during fasting due to lower insulin levels. This can lead to symptoms like dizziness, fatigue, and muscle cramps. For extended fasts (beyond 24 hours), or if you are exercising, replenishing electrolytes is particularly important. A simple pinch of high-quality salt in your water can help with sodium loss, while sugar-free electrolyte supplements can help replenish potassium and magnesium.

What Definitely Breaks a Fast

Any liquid with a significant calorie count, especially those high in sugar, will disrupt the metabolic benefits of your fast. Some common culprits include:

Sugary Drinks: Sodas, juices, and sports drinks are high in calories and sugar.
Milk and Creamers: Dairy products contain calories and will break a fast.
Alcohol: Contains calories and can lead to dehydration.
Protein Shakes: These are designed to provide nutrients and calories and will end a fast.
Bone Broth: While often considered, it contains protein and amino acids that activate the body's growth pathways, technically breaking a fast. It is better used to break a fast gently.

Fasting Liquids: A Comparative Overview


Fasting Type	Water	Black Coffee / Tea	Juice / Soda	Bone Broth
Intermittent Fasting	Yes	Yes (Unsweetened)	No	No (Breaks fast)
Dry Fasting	No	No	No	No
Medical Fast	Plain water only (check doctor)	No	No	No

How to Maximize Hydration on Your Fast

To ensure you stay hydrated effectively and safely during your fast, follow these tips:

Sip Regularly: Drink water consistently throughout the day instead of chugging large amounts at once.
Add Salt: For longer fasts, add a pinch of Himalayan pink salt to your water for a simple way to replace sodium.
Use Zero-Calorie Electrolytes: Consider a supplement if your fast is extended or you are active. Ensure it contains no sugar or artificial sweeteners.
Listen to Your Body: If you experience persistent headaches, dizziness, or fatigue, it's a sign you need to adjust your liquid intake or consider ending your fast.
Time Your Caffeine: If you consume black coffee or tea, consider having it earlier in your fasting window to avoid disrupting sleep.

Conclusion: Listen to Your Fast

The acceptability of drinking liquids while fasting is entirely dependent on your specific fasting method and goals. For most people practicing intermittent fasting, plain water, black coffee, and unsweetened teas are beneficial and encouraged. However, for dry fasting or pre-medical procedures, strict abstinence is required. Proper hydration is a cornerstone of safe and effective fasting, helping to prevent common side effects like dehydration and electrolyte imbalances. Always prioritize your health and consult a healthcare professional, especially for longer fasts or if you have underlying health conditions. For a detailed guide on what breaks a fast, you can refer to authoritative sources(https://www.womenshealthmag.com/weight-loss/a35128842/what-breaks-a-fast/).

Frequently Asked Questions

No, drinking plain water does not break a fast. It has no calories and is essential for hydration during all types of fasts except for a dry fast.

Yes, black coffee and unsweetened tea are generally permitted during an intermittent fast. They contain negligible calories and won't trigger an insulin response. Avoid adding sugar, milk, or cream.

While diet sodas are zero-calorie, some experts are cautious about artificial sweeteners, as they may trigger a metabolic response in some individuals. It is safer to stick to water or naturally flavored teas.

Bone broth contains protein and amino acids, which will trigger an insulin response and break a fast. It is best to save bone broth for breaking your fast gently.

During fasting, the body loses fluids and electrolytes more quickly. Staying hydrated supports metabolic function, helps manage hunger, and prevents side effects like headaches, dizziness, and fatigue.

Electrolytes are essential minerals like sodium, potassium, and magnesium. During prolonged fasts or intense exercise, they can become depleted. Zero-calorie electrolyte supplements can help replenish them and prevent deficiency symptoms.

If you accidentally consume a caloric liquid, your fast is technically broken. The best approach is to simply return to your fasting protocol after the incident. Don't dwell on the mistake; consistency over time is what matters most.

A squeeze of lemon in your water is generally acceptable during a fast, as the small number of calories won't significantly affect your metabolic state. It can make water more palatable and refreshing.