What Can You Drink While Fasting?

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

You’ve likely heard celebs and influencers tout the benefits of various trendy diets, but one buzzy eating plan continues to stay in the spotlight: intermittent fasting. People swear by the benefits of structuring *when* they eat and snack, but the fasting schedule begs a lot of questions. Are there side effects? Will I lose weight? Do I have to give up my morning coffee? What can I drink without breaking my fast?

The latter are the questions that bring us here today. Keep reading for everything you need to know about what you can — and can’t — drink while fasting.

Why What You Drink During Intermittent Fasting Is So Important

Many beverages have calories that can break your fast, trigger an insulin response, and prevent your body from going into autophagy, which is one of the benefits of fasting.

That being said, it’s especially easy to become dehydrated while fasting (no matter what type of fast you’re on). You may not realize, but a lot of your daily fluid needs come from food, and when you avoid eating for a period of time, this means you will need to drink more water or other calorie-free liquids to compensate.

Be intentional about your sipping and aim to drink at least 2.7 liters of water per day. The only time as much plain water as you want is not allowed is if you’re on a dry fast, which personally I would not recommend as it can lead to severe dehydration.

What Not To Drink While Fasting

No matter what type of fast you’re following, these drinks are best avoided during your fasting window:

1. Soda

Soda is loaded with sugar. One cup of Coca-Cola, for example, contains 26 grams — that’s 1 gram over the daily recommended sugar limit for women. Soda is also high in calories, so you’ll want to avoid sipping on this bubbly beverage during a fasting window.

As for diet, zero-calorie, or zero-sugar beverages, these are also a no-go, as they contain artificial sweeteners that can trigger an insulin response.

2. Alcohol

Alcoholic beverages can also be high in calories and sugar. Drinking alcohol on an empty stomach during your fasting window is never a good idea.

3. Smoothies

Well-balanced smoothies make for a great snack or meal option, as they’re loaded with nutrients, minerals, and macro and micronutrients, but they will break your fast.

Commercially available options (prepackaged, store-bought bottles) often have “way too much sugar with little to no fiber to help slow absorption.” My advice? Wait until your fasting period is over and either make your smoothie at home or opt for a piece of fruit.

4. Bone and vegetable broths

Again, although packed with nutrients, bone and vegetable broths are caloric beverages that will fire up your digestive system. These warming beverages should be avoided if you’re sticking to a fast.

That said, for patients undergoing medically supervised longer fasts (i.e., for a procedure like a colonoscopy), these types of broths might be on the approved-to-consume list, as they contribute to a healthy gut and contain protein. Also, drinking bone broth is a great way to break your fast, as the liquid is light on your stomach.

What You Can Drink While Fasting

Okay, but what you can actually drink when fasting may be a little hazy. Below, are what you should know about some of the most popular drinks you might want to consume while doing intermittent fasting, and whether or not they’ll sabotage your fasted state.

1. Coffee

Black coffee is calorie-free, so it’s fine to enjoy during the fasting phase. But adding in sugar, cream, or milk is best avoided, as it can add calories to the drink that can take you out of a fasted state.

If you do want to flavor your coffee during a fast, experiment with calorie-free flavoring from a spice like cinnamon. Save the coffee add-ons for your non-fast windows of time.

Wondering about a keto-approved creamer or MCT oil? This tends to be a little bit more controversial or at least open for interpretation depending on who you talk to.

From a strict fasting standpoint, adding fats to your coffee does break the fast. But I actually do recommend high-quality MCT for people who are consistently doing day-to-day IF programs, especially if their goals are less about cutting calories and more about keeping blood glucose low and giving the body time to rest and digest.

Fats do not have the same sort of blood glucose raising ability of carbohydrates or protein, so they do not really impact your fast if what you’re trying to achieve is improving your overall insulin sensitivity. Plus, many people report better focus in the morning sipping coffee with MCT oil since the medium-chain fats in MCT oil get immediately converted to ketones, which are an alternative fuel source for the brain versus glucose.

Additionally, avoid having more than one cup, or switch to decaf, when you’re fasting. Excessive caffeine, especially on an empty stomach, may increase those jittery feelings which can often increase appetite and the desire to snack. I would also add that caffeine raises cortisol which can cause a cascade of hormonal responses that ultimately leads to an increase in blood glucose, [which is] something we are trying to avoid when fasting.

2. Tea

Just like coffee, tea is naturally calorie-free and fine to have during a fast, so long as it’s simply brewed tea that comes from tea bags, leaves, or flakes. Bottled ice tea is often heavily sweetened, so if you go that route, make sure you’re opting for one that is unsweetened and not loaded with added sugar and calories. Caloric add-ons such as honey, milk or cream should be reserved for non-fasting times, just like with coffee.

Since tea is naturally lower in caffeine than coffee, you can have a bit more during fasts, however I would still recommend opting for decaf when possible.

3. Water and seltzer

Water is naturally calorie-free so there’s no need to restrict it. Water in general is a good idea to sip on during fasting times to ensure hydration but also as a way to fill your stomach and prevent hunger.

If you enjoy flavored water, you can add in a splash of lemon or lime juice (or a splash of another juice) as long as it is a true “splash” (around one tablespoon per 12 ounces) and doesn’t add more than a trivial amount of calories. Carbonated water/seltzer can be treated in the same way as water, as long as it is naturally flavored and calorie-free.

What should you eat while intermittent fasting?

It’s clear that what you drink while fasting contributes to your success, but what you eat (when you’re not actually fasting!) is also key. A main perk of intermittent fasting is that you technically don’t have to alter what you eat, you just have to eat within a certain window of time.

That said, you want to be sure your meals are well-balanced. Prioritize fruits, vegetables, and protein during your feeding window, and focus on foods that are high in fiber and healthy fats. Think quinoa, spinach, apples, avocado, salmon, almonds, sweet potato, and chicken.

You also want to avoid or minimize processed foods, simple carbs, refined sugars, and sugary drinks.

What about taking supplements during a fasting period?

This depends on the fasting schedule you’re following, and you should discuss any supplements with your doctor before beginning to take them. If you fast for a set amount of hours each day, take your supplements during the eating hours (unless otherwise instructed by your doctor or dietitian), since most supplements like a multivitamin are better absorbed when taken with food.

If you practice intermittent fasting that involves fasting on specific days, like the 5:2 diet, taking supplements is still recommended to ensure you are meeting your nutrient needs each day.

Generally, the small amount of calories found in a chewable/gummy/liquid vitamin would not offset a fast day. But do discuss this with your doctor or dietitian first to make sure you can take your supplement on an empty stomach.

Plain water, black coffee, and unsweetened tea are the best beverages to sip while fasting. At the end of the day, you want to consume close to zero calories during fasting periods. By avoiding sweetened drinks like soda and bottled iced tea, as well as caloric add-ons in your hot beverages, you can ensure you follow your IF plan correctly and successfully.

Types Of Intermittent Fasting

Consider these different types of fasting that focus on *when* you can eat. Remember: Always talk to your doctor before overhauling your eating regimen and know that we’re not necessarily endorsing these strategies, just shedding some light on what they involve.

16/8 Method: This is the most popular method that involves fasting for 16 hours each day and limiting your eating window to eight hours. This is relatively easy to follow since it usually involves skipping breakfast and having your first meal around noon, she adds.

5:2 Diet: With this plan, you eat “normally” for five days a week and restrict calorie intake to 500 to 600 calories for two non-consecutive days.

Eat-Stop-Eat: This method involves fasting for 24 hours once or twice a week. So, you would eat dinner one day and fast all the way until dinner the next day.

Alternate-Day Fasting: This method involves fasting every other day. On fasting days, calorie intake is either restricted to 500 to 600 calories or completely avoided.

OMAD (One Meal a Day): OMAD involves fasting for approximately 23 hours and consuming all your daily calories within a one-hour eating window.

The Take-Away

There’s a lot of debate surrounding what you can drink while fasting, but the answer depends on how strict of a fast you’re following. “Clean” fasters skip drinks with calories and sugar content, while “dirty” fasters make exceptions, like a splash of creamer in their coffee or milk in their tea, and might find fasting easier to stick with as a result. No matter what approach you take to beverages, it’s important to break your fast carefully.