We talk a lot about what to eat during intermittent fasting. 

But drinks have calories, too. 

So, what can you drink while fasting?

It’s a good question. And an important one. If intermittent fasting means we can no longer have our morning coffee, we don’t know what we’ll do. [clutches chest] 

These are things we NEED TO KNOW. 

Fasting can’t give you results if you indulge in the occasional beverage treat during your fast, however minimal it may seem. These drinks can spike your insulin or throw a bunch of calories into your system. Yeah, I’m looking at you, Triple Chocolate Frappuccino.

Let’s dive into the science and put this question to bed, so you can stop scratching your head and get on with living your life and achieving your goals. 

After you’ve read this, the words “Will this break my fast?” will never again pass your lips. 

Well, relative to drinks, anyway. 

So, what can I drink during intermittent fasting?

Let’s get definitive about what to drink — and not to drink — when fasting.

Before we dive into what’s what, if you’re not really sure what we even mean by “intermittent fasting,” check out our intermittent fasting for beginners guide first. Then go ahead and take our Simple quiz, where we can help you figure out the best approach for your unique body, preferences, and lifestyle.

1. You can drink water when intermittent fasting. 

You’ve probably been told, “It’s essential that you drink more water!” a thousand times. It’s the kind of advice that becomes background noise after a while. 

But it really matters. Why? Because water is a heavyweight health improver. 

For instance, water:

• makes your brain work better
• energizes your body
• helps curb your appetite
• improves your mood
• helps you sleep well
• may help you lose weight [1]
• boosts your metabolism [2]
• regulates your body temperature
• lubricates your joints
• delivers nutrients to cells
• keeps your organs functioning
• helps prevent infections

Maybe that sounds like just another boring list of “health benefits.” *insert yawn here*

Here’s what it means in real-life terms: if you want your body and brain to feel good and function well, water is a friend that will never fail you. 

2. You can drink mineral water while intermittent fasting. 

Mineral water contains natural minerals, like magnesium, potassium, and calcium, that distilled or tap water doesn’t.

Can those minerals boost your health? Definitely. Research shows a link between mineral water and many short- and long-term health benefits like improved bone health and reduced blood pressure.[3] 

Will those minerals break your fast? Nope. 

3. You can drink sparkling water during intermittent fasting.

Sparkles come from fizzing the water with carbon dioxide gas. Gases have no calories, so there’s no fast-breaking happening here.

Some sparkling water brands contain sodium, which also doesn’t negatively impact your fast. In fact, added sodium may actually be helpful by replenishing electrolytes, which can be lost as your body uses up your glycogen stores. 

4. You can drink lemon water during intermittent fasting. 

Water with lemon has almost no calories, so it won’t spike your insulin levels. 

And what makes lemon water even better? 

Lemon is a rich source of vitamin C and may decrease your hunger during your fast.

Actually, if you like flavored water, adding a fruit wedge or a splash of fruit juice — as long as it is just a splash, which is around one tablespoon — is A-OK. 

Even with this fruit infusion, your drink stays in single-digit calories, and you stay on solid fasting ground. 

5. You can drink coffee while intermittent fasting.

Coffee lovers, you can still enjoy your coffee! 

[pause for sighs of relief]

In fact, given that some studies suggest that caffeine supports ketone production,[4] if you’re using intermittent fasting in conjunction with a keto diet, coffee may give you even better results. 

Be aware that sometimes caffeine hits quite hard on an empty stomach, so notice how it makes you feel. If it makes you jittery or shaky, decaf might be a good swap. 

All that being said … 

While coffee itself is cool, coffee with added “stuff” is not. An average cup of black coffee has one calorie. All good. Your fast is still intact. 

A coffee with a splash of milk — about a tablespoon or two — stays in single-digit calories. Still good, so long as you stick to one cup during your fasting window. 

When we start adding creamer or ordering specialty coffees at your local coffee house, though, the calories start ramping up. 

And bulletproof coffee? Yeah, that’s a no-go. The butter or MCT oil that makes your coffee bulletproof is fat which, while decreasing your hunger and cravings, will spike your insulin.

So if you love your coffee black or with a touch of milk, and the answer to the question “Can you drink coffee while fasting?” has been holding you back from starting your intermittent fasting journey, consider that hurdle cleared. 

Go take our Simple quiz and make today the day you kick your efforts to reach your goals up a notch!

6. You can drink tea while intermittent fasting. 

The same rules apply here as with coffee.

Tea is on the menu, but it’s gotta be sugar-free, and only one cup with a splash of milk is allowed. 

So while Long Island Iced Tea is out of the question (sorry!), why not let your intermittent fasting be your doorway into the wonderful world of Teas You Have Not Yet Explored?

Black, green, oolong, lapsang souchong, and all manner of herbal teas are brilliant ways to bring a little flavor to fasting.

Not just flavor either — tea may play a supportive role in gut health, green tea could increase your feelings of fullness and help with weight loss,[5] and the caffeine and theanine in tea can improve your mental alertness.[6]

Who knew tea was such a powerhouse?! 

7. You can drink apple cider vinegar during intermittent fasting. 

This is admittedly one of those drinks that falls into that much-hated place in nutritional science: the gray area. 

Some say you can drink it during intermittent fasting. Others say you can’t. 

At Simple, we say yes. Adding a spoonful of apple cider vinegar to water won’t affect your fast. The calories are negligible. 

Actually, we find apple cider vinegar kinda helpful when intermittent fasting because it can help you feel full and squash annoying cravings.

Just don’t drink it neat. (Bleh.)

8. You can drink diet soda during intermittent fasting. 

According to our science team, up to two diet sodas per day are unlikely to break your fast.

Diet soda is another “gray area” drink, though, this time due to its artificial sweeteners. 

Even though they’re calorie-free, some research suggests artificial sweeteners can affect your blood sugar levels.[7]

Pay attention to your body if you choose diet soda as a fasting drink. Notice:

• Does it kick your cravings up a notch? 
• Does it increase your hunger levels? 

Some people find that artificial sweeteners have these effects. If that’s you, diet soda is best left off your intermittent fasting drinks list. 

Another option here could be stevia-sweetened soda (if your stomach gets along with stevia, of course). Stevia doesn’t contain any macronutrients, so it can’t cause an insulin response. 

That concludes our “What can I drink when fasting?” rundown. Now, let’s look at what you can’t. 

What drinks should I avoid while fasting?

Here, we’re looking for drinks that contain calories. 

If you’re doing intermittent fasting for weight loss, there are extra benefits to be had from avoiding these kinds of drinks.

Most of them are obvious: Does a whipped cream eggnog latte from your favorite coffee house contain calories and therefore break your fast? Of course it does. 

But some drinks are more subtle. They might have the “healthy” label attached, making us think they’re fasting-safe even though they’re not. 

Let’s review those sneaky drinks.

1. You shouldn’t drink coconut water during your fast.

Coconut water is a fast breaker for the simple reason that it contains carbohydrates.

Save it for your eating window.

2. You shouldn’t drink milk during your fast. 

With all milks, whether dairy or plant-based, it’s an issue of quantity.

One or two tablespoons of milk in your coffee or tea won’t bust you out of a fasted state. 

But a quarter cup or more will break your fast because milk contains calories and carbs. Even though there’s also protein and fat, which will slow down the rise in your blood sugar, drinking milk will still trigger an insulin response. 

So, during your fasting window, stick to one cup of tea or coffee. If you go beyond that, the calories will start to tick up. 

3. You shouldn’t drink bone broth during your fast.

Bone broth is good stuff from a health perspective, and that’s because it provides quality nutrients like protein and fat. 

Those nutrients need to be digested by your body, which is precisely what kicks you out of ketosis.

4. You shouldn’t drink fruit juice or smoothies during your fast.

When you eat a piece of fruit, there’s fiber as well as juice. That fiber, to your blood sugar, is key. 

Fiber slows down how quickly your body absorbs the sugar in the juice. That means eating the whole fruit, even though it contains calories and fructose, doesn’t spike your blood sugar. It raises it, but more slowly.

In contrast, fruit juice will have a faster and bigger impact on your blood sugar levels since it doesn’t have fiber like a piece of fruit does. 

Smoothies, which are basically just a bunch of juices all smushed up together, have a similar impact.

All in all, juice is a fast breaker. 

5. You shouldn’t drink alcohol during your fast. 

OK, alcohol isn’t technically a drink that tries to convince us of its healthfulness, so we probably don’t need to say this.

But, just in case you’re wondering, “Hey, when fasting, can I drink vodka?” because vodka is clear and someone once told you clear spirits have no calories, we’re here to say: 

Drinking alcohol will break your fast.

While alcohol is not, in fact, a macronutrient, alcoholic drinks do contain calories. They can also bump up your cravings and lower your resolve, making you extra snackish, especially on an empty stomach. 

When you’re fasting, if someone offers you a beer, just say no. 

Why is what you drink (or don’t drink) so crucial?

As we just said, the human body needs water. This is fundamental — it’s not something we can hack or override. 

When you’re fasting, it’s really easy to become dehydrated. Maybe you forget to drink. Or misinterpret your thirst as hunger. And because as much as 20% of your daily fluid intake comes from your food, when you restrict your eating times, you’re also restricting your hydration because you’re not getting any water from food. 

When you drink during fasting, the goal is twofold:

1. Stay hydrated.
2. Keep your fast intact.

Our aim is to avoid drinks that cause your body to release insulin. 

Why? Because insulin disrupts the benefits of intermittent fasting.

Here’s how: 

When you eat throughout the day, your body gets its energy from the food you eat. It calls on insulin to help process this food and turn it into energy, fat, muscle, and brain power.

In contrast, when you fast for a prolonged period, your body has to draw energy from the glucose it already has stored. Once that’s all gone, it can start burning fat for energy instead — a process called ketosis.

This metabolic switch to ketosis is part of what we seek to stimulate through intermittent fasting.

And it’s how intermittent fasting creates reduced insulin resistance and increased insulin sensitivity, one of its signature benefits. Drinking caloric drinks disrupts that process.

What can you eat during intermittent fasting? 

It stands to reason that if there are best practice guidelines for what to drink during eating and fasting windows, there are also guidelines for what you can eat during them, too. 

You want to avoid eating more than ten calories of anything during your fasting window to avoid snapping your body out of its fasted state. 

But as far as your eating windows go, what you can eat during intermittent fasting is totally up to you. Your goals, preferences, and nutritional needs should take the reins here, but no food is inherently bad or off-limits. To maximize results, build your meals around nutrient-dense foods like the ones on our intermittent fasting foods list. 

What is intermittent fasting?

Intermittent fasting is an approach to eating that’s less about what you eat and more about when you eat. 

The core of the practice is as follows: 

For a pre-specified, repeated amount of time, you take a break from eating. That break is known as a fast. 

How and when you fast depends on which method you choose. There are lots of ways to do intermittent fasting. 

Some approaches are more studied than others and are fairly reliable at creating weight loss and improving health by lowering blood pressure, regulating blood sugar, and decreasing cholesterol. 

Others are a bit more … out there. Less researched. Less advisable (without a doctor to supervise). 

And some have different rules on what you can drink while fasting.

For instance, some intermittent fasting approaches involve not drinking at all or drinking only water. We don’t recommend you try these, and we’ll explain why in a moment. 

Types of intermittent fasting

Before we outline different fasting schedules, there are two factors to take into account: 

1. You should always consult with your healthcare team before making any significant changes to your lifestyle or eating habits. 
2. At Simple, we don’t recommend fasting schedules where you eat nothing or a limited amount of calories for 18+ hours — especially if you’re planning to fast daily or several times a week. These schedules involve more potential risks and safety concerns, and there isn’t really any evidence to suggest they’re more effective than less restrictive approaches. 

With that in mind, let’s look at the options briefly.

Time-restricted eating (TRE)

TRE intermittent fasting schedules are known by their numbers, like 12:12, 14:10, 16:8, etc. Those numbers tell you the fasting / eating schedule. 

For instance, with 16:8 intermittent fasting, you fast for 16 hours and eat within the remaining 8 hours every day.  

The Warrior Diet

The Warrior Diet is a version of time-restricted eating: 

A 20-hour fast followed by a 4-hour eating window. 

With such a short time to meet your nutritional needs, we don’t recommend this option unless you’ve got that medical seal of approval.

The 5:2 diet

The 5:2 diet is arguably the most famous member of the intermittent fasting family. 

With 5:2, you eat your regular diet five days a week and drop your food intake to 500/600 calories on the other two days. 

Even if you can eat as you normally would for five days, the serious restrictions on the other two make this schedule another we don’t recommend without support from your healthcare team. 

Alternate-day fasting (ADF)

Alternate-day fasting takes the 500/600 calorie aspect of the 5:2 schedule to the next level. 

You fast every other day. On fast days, you eat 500/600 calories. 

This every-other-day pattern equals three or four pretty restrictive fasting days a week, so again, it’s not on our list of options unless your healthcare team is on board.

Eat Stop Eat

Eat Stop Eat is an approach that, like 5:2, has two fast days a week. Unlike 5:2, though, these fast days are zero-calorie ones. 

You’d eat one meal on your fast day, and that’s it until the same time the next day: a 24-hour fast in total. 

With such hefty restrictions, you can bet this schedule is on our “no go without medical approval” list.

Water fasting

Water fasting is another zero-calorie fast, which can be anything from 24–72 hours (some people go a lot longer). During the fasting period, you only drink water. 

So, it’s another approach we don’t recommend unless you have medical supervision.

Dry fasting

Dry fasting is not only no food, but no drinks of any kind either. 

Any intermittent fasting schedule you follow, whether it’s TRE, 5:2, or ADF, you can make into a dry fast by simply not drinking anything.

Because the human body needs water to function, we really don’t encourage anyone to try this.