Can You Drink Water When Fasting?

Intermittent fasting is an eating pattern in which you abstain from food for certain periods of time, often either 12–16 hours each day or 24 hours once or twice per week.

Fasting results in lower blood sugar and insulin levels. Yet, solid foods increase your blood sugar levels and stimulate the secretion of insulin, which is the hormone that carries sugar from your bloodstream to your cells (1).

Solid foods break your fast and cause your body to reenter the fed state, which lasts for several hours as your body breaks down and digests your food (1).

However, water doesn’t affect blood sugar or insulin levels. Therefore, you can safely drink it while intermittent fasting.

In fact, it’s recommended to drink water to help you stay hydrated during an intermittent fast.

What about dry fasting?

The main exception is dry fasting, which restricts all foods and liquids, including water, for a specific amount of time.

Some people do a dry fast while intermittent fasting.

However, because dry fasting may be linked to dehydration and other health complications, you should talk with a healthcare provider before trying it.

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Water does not affect blood sugar or insulin levels and is usually permitted during intermittent fasting. Dry fasting is the main type of fasting that doesn’t allow water.

If you’re preparing for a medical procedure, you’re often advised to fast for 8–12 hours beforehand.

Typically, this type of fasting helps ensure that you have an empty stomach during surgery, minimizing the risk of complications like vomiting, regurgitation, and aspiration (2).

Because clear liquids like water are quickly digested, some medical professionals may allow you to drink water up to 2 hours before your procedure (3, 4).

Still, it’s very important to check with your medical team about specific guidelines for drinking water prior to your procedure.

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While clear liquids are sometimes permitted for up to 2 hours before medical procedures, it’s best to check with your healthcare team for specific guidance.

Aside from water, you can drink other calorie-free beverages to keep you hydrated while doing intermittent fasting. These include:

• black coffee
• unsweetened tea
• flavored water
• sparkling water
• lemon water

Bone broth is sometimes permitted depending on the strictness of your fast. Although it contains some fat and calories, small amounts may provide important vitamins and minerals during longer fasts.

Safe liquids for medical procedures

Prior to medical procedures, clear liquids are also sometimes allowed. These include (5):

• sparkling water
• flavored water
• clear broth
• pulp-free fruit juice
• plain gelatin
• unsweetened tea
• clear ice pops

Be sure to check with your healthcare team for more details on which liquids you can drink before your surgery or procedure.

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In addition to water, several other calorie-free drinks are allowed during intermittent fasting. Certain clear liquids may also be permitted before medical procedures.

Certain drinks contain calories or sugar and can break your fast.

Similarly, many beverages may increase the risk of complications during a medical procedure and should be avoided.

Some examples of drinks to avoid while fasting include:

• soda
• sweet tea
• sports drinks
• coffee with milk, cream, or sugar
• energy drinks
• smoothies
• milk
• alcohol

Pulp-free fruit juice is sometimes allowed prior to medical procedures but banned during intermittent fasting due to its sugar and calorie content.

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Many drinks break a fast and may increase the risk of complications during a medical procedure.

Drinking water during an intermittent fast is usually permitted.

In some cases, water and other clear liquids may also be allowed for up to 2 hours before medical procedures, although specific guidelines vary.

Other fast-friendly drinks include black coffee, unsweetened tea, and flavored or sparkling water.