【Choose These and You Won’t Go Wrong】What Can You Drink While Fasting? How to Choose Water, Tea, and Coffee, and Drinks to Avoid

“When you’re fasting, you can only drink water, right?”

Have you ever felt that kind of worry when you were about to start fasting?

Actually, this is one of the most common misconceptions out there.

Even while fasting, you can drink plenty of water, tea, black coffee, and more, and the drinks you choose can make a big difference in how hungry you feel.

In this article, I’ll lay out clearly what you can and can’t drink while fasting, and share some hydration tips to help you keep up intermittent fasting (IF) comfortably.

The One Simple Rule That Separates OK Drinks from Off-Limits Drinks While Fasting

When you’re deciding whether a drink is OK during a fast, there’s one rule I’d like you to remember.

That rule is: “Does it stimulate insulin?”

Insulin is a hormone released when your blood sugar rises, and it sends your body the signal, “Nutrients are coming in right now, so there’s no need to burn fat.”

If your insulin goes up while you’re fasting, it can spoil the fat-burning mode you’ve worked so hard to reach.

Think of it like a factory that has finally closed for the day, only to have a truck pull up and start unloading a delivery.

The factory has to start receiving goods all over again, and the whole point of the day off is lost.

That’s exactly why, during a fast, “what you drink” matters just as much as “what you don’t eat.”

Any Drink with Calories Is Off-Limits

Drinks that contain calories, such as coffee or tea with sugar, juice, milk, and smoothies, stimulate insulin, so they’re off-limits.

I completely understand the feeling of “just a little won’t hurt,” but even a small amount can significantly reduce the benefits of your fast.

Zero-Calorie Drinks Are OK

Drinks like water, tea, and black coffee that have almost zero calories and barely stimulate insulin are fine to drink even while fasting.

When in Doubt, Check the Label

The trick to telling them apart is to check the ingredients list and the nutrition facts on the package.

Just by checking these three points, you’ll be able to tell in almost every case whether a drink is OK during your fast.

If you pick drinks based only on an image of “looks healthy” or “seems good for you,” you may end up with something surprisingly high in sugar, so be careful.

I also explain the basic idea behind 16-hour fasting in “The Complete Beginner’s Guide: What Is Intermittent Fasting? Types, Benefits, How to Do It, and Why You Might Not Be Losing Weight, Explained Simply.”

3 Reasons Drinks Matter So Much During a Fast

During a fast, drinks do much more than just quench your thirst.

Here are three reasons you should make sure to drink enough while fasting.

Reason 1: You Lose the Water You Normally Get from Food

We don’t usually think about it, but we actually get a lot of our water from food.

That’s because rice, miso soup, vegetables, and fruit are all full of water.

When you fast, all of this “water from food” disappears.

If you go about your day the same way as always, it’s easy to become dehydrated without noticing.

Also, while fasting, minerals such as sodium and potassium (nutrients that help keep your body in balance) leave your body through sweat and urine.

So rather than relying on water alone, it’s also important to replenish minerals during your eating window with vegetables, miso soup, and the like.

Reason 2: Drinks Help Ease Hunger

When you’re just starting out with fasting, learning to deal with hunger is one of the biggest challenges.

When a drink enters your stomach, your stomach expands, and the hunger signal tends to settle down for a while.

Especially for people who are used to always putting something in their mouth, drinks become a reliable ally that fills that “something to munch on” urge.

Reason 3: Drinks Keep Things Flowing in Your Body

Water is the main ingredient of your blood and lymph (the fluid that carries waste through your body).

It’s just like a river: when the water level drops, the flow becomes sluggish.

It’s also said that when your body runs low on water, your blood tends to become thicker.

By drinking enough, you keep things flowing in your body, which makes it easier to feel light and clear-headed even during a fast.

It’s especially important to drink more consciously than usual in summer, when you sweat easily, and on days you exercise.

In other words, the drinks you have while fasting are your “partner” for keeping your fast comfortable.

Drinks to Reach For While Fasting: My Top 5 Picks

Each of the drinks that are OK has its own welcome benefits that support your fast.

Rather than drinking them simply “because they’re allowed,” let’s make these drinks work for you and make fasting even more comfortable.

① Water (Room Temperature, Warm Water, Sparkling Water)

When it comes to fasting, water is the foundation.

Water can temporarily curb your appetite, and drinking some when hunger hits often helps you feel calmer.

If room-temperature water is hard for you to drink, I recommend plain warm water.

It warms your stomach and tends to settle your appetite.

Sparkling water is also helpful when hunger is strong, because the fizz makes you feel more satisfied.

However, some flavored sparkling waters, like lemon-flavored ones, contain sweeteners or sugar, so be sure to check the label.

There’s no rule about what kind of water to drink, but hard water you’re not used to can loosen some people’s stomachs, so starting with soft water is the safer choice.

② Green Tea, Hojicha, and Genmaicha

Japanese teas are a powerful ally during a fast.

The catechins in green tea help support fat burning and may boost the effects of your fast even further.

Hojicha and genmaicha are relatively low in caffeine, so they’re well suited for staying hydrated in the late afternoon and evening.

Drinking green tea during my morning fast has become a habit for me.

I love how it’s gentler on my stomach than coffee and gives me a gradual, refreshing lift.

Some people find that strong green tea on an empty stomach irritates their stomach, so if you feel queasy, try brewing it weaker.

③ Black Coffee

Coffee is a go-to drink during a fast.

Caffeine helps suppress appetite and also promotes fat burning.

That said, absolutely no sugar and no milk.

If you’re not used to black coffee, it may be tough at first, but once you get used to it, coffee with milk will actually start to feel heavy.

The best time to drink it is in the first half of your fasting window (in the morning).

In the late afternoon and evening, caffeine can affect your sleep, so be careful.

④ Herbal Tea (Unsweetened)

Many herbal teas, such as chamomile, peppermint, and rooibos, are caffeine-free, so you can drink them with peace of mind.

Chamomile also has a calming effect on the stomach and can sometimes ease stomach discomfort during a fast.

Adding honey or sugar weakens the effects of your fast, so drink it plain.

⑤ Mugicha

Mugicha is caffeine-free and contains minerals, making it perfect for fasting in summer or for staying hydrated before bed.

It’s also almost zero calories, so you can drink it worry-free during a fast.

When hunger at night feels tough, slowly sipping mugicha that isn’t too cold tends to help you feel calmer.

Watch Out! Drinks That Are Surprising Pitfalls

You might think anything labeled “zero calories” or “unsweetened” is safe… but in fact, some drinks still call for caution.

Zero-Calorie Drinks and Drinks with Artificial Sweeteners

“Zero-calorie” colas and sweet sodas may seem fine at first glance, but artificial sweeteners may trigger an insulin response.

If you want to get the most out of your fast, it’s safest to avoid zero-calorie drinks.

The sweet taste can also make some people crave sweets even more, which is another reason to be careful.

Too Much Caffeine

Coffee is helpful during a fast, but drinking too much can be harsh on an empty stomach.

Ideally, keep it to about 2 to 3 cups a day.

If you feel heartburn, an upset stomach, or heart palpitations, try cutting back or switching to mugicha or herbal tea.

Kombucha and Enzyme Drinks

Kombucha and enzyme drinks, which have become popular lately, have a healthy image, but many of them contain sugar and calories.

Make it a habit to always check the label.

“Health-oriented” drinks like vegetable juice, smoothies, and drinkable yogurt also often have fruit juice or sugar added to make them easier to drink.

Drinking these during a fast is essentially the same as having a “liquid meal.”

Keep in mind, too, that liquids are absorbed faster than solid food, so they tend to raise blood sugar more easily.

Sports Drinks

You might be tempted to use sports drinks to replenish minerals, but many products contain sugar.

If you want something during a fast, choose a sugar-free electrolyte tablet dissolved in water.

Alcohol

Alcohol has calories, and on an empty stomach it’s absorbed more easily, so you get drunk faster.

Once you’re tipsy, the brakes on your appetite loosen too, which can lead to binge eating when you break your fast.

If you do drink, enjoy a moderate amount during your eating window, together with food.

Even “healthy-looking drinks” are off-limits during a fast if they contain calories or sugar.

Please try to build the habit of reading labels.

Hydration Tips That Make Fasting Easier to Stick With

Now that you know which drinks to choose, here are some tips to make your fast even more comfortable.

When You Feel Hungry, Drink Water First

The “hunger” you feel during a fast is actually often just thirst.

When you feel hungry, try drinking a glass of water first.

That alone often eases the hunger.

Waves of hunger don’t last forever; they usually pass after a while.

Often, slowly sipping warm tea or warm water is enough to ride out a wave of hunger.

Drink Small Amounts Often

It’s said that drinking small amounts frequently helps water reach your whole body better than drinking a lot at once.

It’s like pouring a bucket of water onto a bone-dry flowerpot: instead of soaking into the soil, it just runs straight out the bottom.

Keeping a water bottle on your desk or by your bed is a great way to naturally drink more often.

Have Coffee in the First Half of Your Fast

The best time to drink coffee is during the morning part of your fast.

That way you can make the most of caffeine’s alertness boost and appetite-suppressing effects.

In the late afternoon and evening, it can affect your sleep quality, so try to cut back as much as possible.

Lack of sleep can also throw off your appetite, so choosing caffeine-free drinks from the late afternoon on is the safer bet.

How Much to Drink Per Day

It’s said that the ideal amount of fluid is about 3 to 4% of your body weight.

For someone who weighs 60 kg (132 lb), that works out to roughly 1.8 to 2.4 L per day.

During a fast, you lose the water you’d normally get from meals, so it’s important to consciously drink a bit more.

During sweaty seasons or on days you exercise, make a point of drinking more than this guideline.

Switch Up the Temperature

Cold drinks go down easily and leave you feeling refreshed.

On the other hand, some people find that drinking only cold beverages chills their digestive system and upsets their stomach.

Use warm water or hot tea in the morning and in colder months, and room-temperature water on hot days or after exercise, adjusting to the season and how you feel.

Drink More on Days You Exercise

On days you walk or do strength training while fasting, you lose more water through sweat than usual.

Make a habit of sipping water or mugicha before, during, and after your workout.

If you sweat heavily or feel dizzy, don’t push yourself; it’s important to end your fast and eat something.

How to Choose Fasting-Friendly Drinks at a Convenience Store

When you’re out or at work, you probably often buy drinks at a convenience store.

Convenience stores carry countless drinks, but once you know how to choose, you won’t hesitate.

Easy Picks at the Convenience Store

The key is to choose drinks labeled “unsweetened,” “black,” “no sugar,” or something similar.

Fresh hot coffee from the counter is also fine during a fast, as long as you don’t add sugar or milk.

Drinks to Avoid at the Convenience Store

On the flip side, many of the drinks that are easy to grab at a convenience store aren’t suited to fasting.

Save café lattes, fruit-flavored milk, sweetened canned coffee, sports drinks, and zero-calorie colas for your eating window, or avoid them altogether.

In particular, flavored waters that contain fruit juice or sugar are hard to tell apart by looks alone, even if they say “water” on the label.

When you pick up a bottle, try to make it a habit to pause for a moment and look at the ingredients list.

Don’t Be Fooled by Package Wording

One thing to watch out for when choosing drinks at a convenience store is labels like “lightly sweetened,” “low sugar,” or “less sweet.”

These words don’t mean “zero sugar”; they only mean the product has less than a regular one.

Also, be careful with “reduced calorie,” since that doesn’t necessarily mean zero calories.

When in doubt, the surest approach is to check the “energy (calories)” and “carbohydrates” numbers on the nutrition facts on the back.

What About Drinks Marketed with Health Claims?

Teas and other drinks that claim to slow the absorption of fat or sugar are designed to be drunk with meals in the first place.

If they’re unsweetened, drinking them during a fast is fine, but you shouldn’t expect any special benefit from having them while fasting.

Rather than going out of your way to buy pricey drinks, think of regular unsweetened tea or water as perfectly good enough.

Even at a convenience store, if you make it a habit to look for the word “unsweetened,” you’ll almost never go wrong when choosing drinks during a fast.

Frequently Asked Questions About Drinks During a Fast

Making Fasting Even Easier to Stick With

If you’re fasting for the first time, I recommend keeping it simple and narrowing it down to just three drinks: water, green tea, and black coffee.

You don’t have to overthink anything, and all three are easy to get, so it’s easy to keep going.

When I first started fasting, I got through it with just these three myself.

The first few days are hard because you’re not used to it, but after about a week, you’ll start to find black coffee genuinely delicious.

Just sorting out what you drink during your fast makes hunger much easier to handle.

Starting today, take another look at how you choose your drinks.

Also, if you take medication for a chronic condition, or if you’re pregnant or breastfeeding, it’s important to talk to your doctor before you start fasting.

For tips on choosing your first meal after a fast, check out “Stabilize Your Blood Sugar with Your First Meal After a 16-Hour Fast! Which Foods Help Boost Fat Burning?“

If drinks alone aren’t enough to get you through the hunger, give the support supplement I use while fasting a try.

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