7 Liquids to Drink While Fasting

The best liquids to drink while fasting are zero-calorie or very low-calorie options. Water, unsweetened black coffee, and unsweetened tea are the most common picks. These tend not to break a fast as they add little or no calories. Individual responses may vary, so pay attention to how your body feels throughout.

Not every drink works during a fast. Some beverages carry hidden calories, often in the form of carbohydrates, that may interrupt your progress before you even realize it. The good news is there are several practical options that fit most fasting routines, whether you follow a 16-hour fast with an 8-hour eating window (16:8) or a longer schedule.

This guide covers seven popular fasting-friendly drinks, explains what you can add to your water, and answers common questions such as whether diet soda counts. If you’re trying to figure out what to sip during your fasting hours, you’re in the right place.

Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It’s advisable to consult a healthcare provider before embarking on a fasting regimen.

What Liquids to Drink While Intermittent Fasting

The best liquids to drink while intermittent fasting are those with zero or negligible calories. These tend to keep you hydrated without adding fuel that may interrupt your fast. Below are seven options many people reach for during their fasting hours.

1. Plain Water

Plain water is the most straightforward choice for intermittent fasting water intake—it has zero calories and zero carbs. It’s unlikely to break your fast or affect your blood sugar. Still water, sparkling water, and seltzer all count, and the latter two can often satisfy flavor cravings.

Drinking water during a fast may offer potential benefits such as supporting digestion and healthy fluid levels for muscle and brain function (1). If plain water feels dull after a while, the next sections cover simple ways you can add variety.

2. Unsweetened Black Coffee

Unsweetened black coffee is one of the most popular drinks during fasting hours. Intermittent fasting coffee tends to work well as it contains very few calories and has little effect on blood sugar for most people.

Caffeine has been studied for its potential effects on alertness and cognitive function (2). It may also help support energy levels and may support energy use during fasting periods (3). You should keep in mind that individual responses to caffeine vary.

A splash of milk or cream adds calories and may affect ketosis for those following a strict low-carb plan. To keep your fast as clean as possible, plain black coffee tends to be the go-to.

3. Unsweetened Green Tea

Unsweetened green tea is a low-calorie option that fits comfortably into fasting hours. It contains few calories and may support body weight management for some people (4), although individual responses may vary.

Some research has explored links between green tea and metabolism and brain function (5). Green tea also contains caffeine (6), so it may offer some similar effects to black coffee during a fast.

One thing to note: some green tea blends carry small amounts of carbs. Sticking to plain, unsweetened versions tends to be the most straightforward approach.

Read more: Green Tea Intermittent Fasting: Potential Effects and What to Know

4. Herbal Tea

Herbal teas such as chamomile, peppermint, and ginger are popular drinks during intermittent fasting. They contain few calories and may offer a range of supportive effects (7, 8).

Here’s a quick look at three common options:

• Chamomile tea has been studied for its potential effects on relaxation and sleep quality (9).
• Peppermint tea may help support comfortable digestion and ease bloating for some people (10).
• Ginger tea has been studied for its potential digestive and comfort-related effects (11).

These teas add flavor and variety to fasting hours without adding sugar, as long as you keep them unsweetened.

BetterMe: Health Coaching app can help you build a more structured approach to your wellness routine with meal plans, workouts, and habit-tracking tools. Start using the app to explore options that may support your personal fitness and nutrition goals.

5. Sparkling Water

Sparkling water has no calories or carbs, which makes it a refreshing alternative to still water during a fast. For many people, the fizz can make fasting hours feel a little more enjoyable.

Some research has suggested that sparkling water may support digestion and help with feelings of fullness for a time (12, 13), although individual responses may vary. Always check labels—some flavored sparkling waters contain added sugars or sweeteners that may break a fast. Sugar-free, unsweetened versions tend to be the most suitable pick.

6. Apple Cider Vinegar

Apple cider vinegar (ACV) is a popular addition to fasting routines, but it does carry a few calories. Some research has explored links between ACV and digestion, body weight management, and blood sugar response (14).

A small, diluted amount may fit some fasting approaches, but it still contains calories. A few practical tips:

• Always dilute ACV in water to reduce the chance of stomach discomfort and keep the calorie density low
• Sip through a straw to limit contact with your teeth
• Add a pinch of baking soda to soften the acidity if needed

Keep the amount modest and notice how your body responds.

7. Black Coffee With MCT Oil

Black coffee with MCT oil is a go-to for many people who are following low-carb eating plans. MCT oil—short for medium-chain triglyceride oil—contains fats that the body can use relatively quickly for energy (15).

Adding MCT oil to coffee may help support energy levels and may support energy use during fasting periods. It may also support feelings of fullness (15). As MCT oil contains calories, keeping to a small amount—around 1-2 tablespoons—tends to work better for those monitoring their intake.

Some people notice changes in how their body responds to MCT oil. Monitor how you feel and adjust as needed. Individual responses may vary.

Read more: Intermittent Fasting and Running: What to Know Before You Start

What Can I Put in My Water While I’m Fasting?

You can add a few low-calorie extras to your water without breaking your fast for most people. Water is the only true zero-calorie drink, but small additions can add flavor, though whether they fit depends on the fasting approach you follow. Here are some suitable options:

• Lemon or lime: A squeeze adds a little flavor along with vitamin C and antioxidants. Skip added sweeteners.
• Apple cider vinegar: A small, diluted amount is an acceptable addition during fasting hours.
• Salt: A pinch may help replenish electrolytes, complementing hydration during your fast.
• Herbs or spices: Mint, basil, cinnamon, or ginger can add flavor and may offer potential benefits. Keep them unsweetened.

These additions keep your water interesting while helping you stay hydrated. Try different combinations to find what you enjoy most.

What Should I Drink on a 7-Day Fast?

Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It’s advisable to consult a healthcare provider before embarking on a fasting regimen—this is particularly important for a 7-day fast, which is an extended period that calls for professional guidance.

A 7-day fast is an extended fast that should be discussed with a qualified healthcare professional. This article doesn’t provide an individual drink plan for it.

Broth may be worth considering for several reasons:

• Nutrients and electrolytes: Broths supply some minerals that may become depleted during a longer fast (16).
• Gentle digestion: Broth tends to be easy on the digestive system and provides nutrients, including those that support bones and cartilage, in a simple, accessible form (16).
• Appetite support: Warm, savory flavors may help manage hunger and keep you feeling more settled.
• Variety: A little broth can make the experience more manageable day to day.

You should keep in mind that broth may break your fast or affect ketosis, depending on the ingredients and the amount you consume.

Will Coke Zero Break My Fast?

Coke Zero is unlikely to break a fast in terms of calories, as it contains zero calories and carbs. However, it does contain artificial sweeteners—aspartame and acesulfame potassium (Ace-K)—and some research has suggested that these tend not to significantly affect blood sugar or insulin response for most people (17), although individual responses may vary.

Whether Coke Zero fits your fast will depend on your personal goals. If your aim is to consume only water during your fast, particularly for a religious fast, it may be worth skipping. Ultimately, it comes down to personal preference and how your body responds.

One thing to consider: diet sodas may increase cravings for sweet foods for some people, which can make fasting hours feel harder (18). Some people may also experience headaches and/or bloating with these artificial sweeteners. Listen to your body and go with what feels right for you.

BetterMe can help you add more structure to your daily wellness routine with workouts, meal planning tools, and habit-building features. Explore the app and take a practical step toward a routine that feels more manageable for you.

Allowed Drinks During Intermittent Fasting

The table below gives a quick overview of common allowed drinks during intermittent fasting. Use it as a handy reference to see what tends to fit a fast and what may not.

FAQs

• What are the allowed drinks during intermittent fasting?

The allowed drinks during intermittent fasting are mainly zero-calorie or very low-calorie options, including water, black coffee, and unsweetened teas such as green, black, or herbal tea. Diluted apple cider vinegar and a small squeeze of lemon or lime in water are also suitable additions for most people. These drinks during intermittent fasting tend not to trigger a significant insulin response, but individual responses may vary.

• Will 20 calories break a fast?

20 calories may break a fast, depending on the source of those calories. Even a small amount can trigger an insulin response for some people, which may interrupt a fast or affect ketosis (19). To stay on track, many people stick to zero-calorie options or keep additions to minimal amounts, such as a little apple cider vinegar or a squeeze of lemon juice. Individual responses may vary.

• What are the best zero-calorie drinks for intermittent fasting?

The best zero-calorie drinks for intermittent fasting are plain water in still, sparkling, or seltzer form. Black coffee and unsweetened tea have negligible calories and also tend to work well for most people. With any intermittent fasting zero-calorie drinks, it’s worth checking labels for hidden sweeteners or added flavors. These zero-calorie drinks intermittent fasting staples help keep your fast simple and your hydration on track.

• Will 50 calories break a fast?

50 calories may break a fast, as it’s a more significant amount than trace additions. Depending on the source, these calories could trigger an insulin response and interrupt your fasting routine, although different fasts will accept very small amounts of calories during the fasting window. Most people aim to avoid calorie-containing drinks during fasting hours to keep things consistent. If you want more variety, intermittent-fasting-allowed drinks with zero or minimal calories tend to be the more suitable choice.

• Does coconut water break a fast?

Yes, coconut water tends to break a fast as it contains natural sugars and carbohydrates that may raise blood sugar and trigger an insulin response (20). If concerns about coconut water breaking a fast have come up for you, it’s generally best to save it for your eating window. Individual responses may vary, but most people following a strict fast choose to avoid it during fasting hours.

The Bottom Line

Choosing the right liquids to drink while fasting doesn’t need to feel overwhelming. Water, black coffee, and unsweetened tea are the most practical fasting drinks for most people, and small additions such as lemon or ACV can add variety without much impact. Everyone’s experience is different, so use this as a starting point, pay attention to how your body responds, and adjust your routine from there.