Can you drink sparkling water while intermittent fasting

Intermittent fasting (IF), an eating style that's typically paired with high-protein or keto diets, begs a lot of questions, especially if you're new to it. You might be curious what type of fasting schedule you should try, what the legit health benefits are, whether you'll experience any side effects, and what kind of weight-loss results you can expect. Another common question is whether you can have beverages, like coffee and water, during your fasting periods.

The short answer is: It depends on the beverage and the type of IF diet you're following (different types of intermittent fasting, from dry fasting to the Warrior Diet, have different guidelines). But a good rule of thumb is to avoid any drinks that have any calories while you're fasting, says New Jersey-based dietitian Erin Palinski-Wade, RD, author of 2 Day Diabetes Diet.

Consuming any carbs, proteins, or fats when you're trying to maintain a fasted state can negate the weight-loss benefits of intermittent fasting, she says. IF diets are also thought to lead to a reduction in insulin resistance and help control blood sugar, both of which may reduce your chances of becoming diabetic. These benefits can be quickly canceled out if you consume too many liquid calories during a period of what should be a fasted state.

Here's what you should know about all some of the most popular drinks you might *want* to consume while doing intermittent fasting, and whether or not they'll take you out of a fasted state.

Coffee

You can drink it black. 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,” says Palinski-Wade. “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,” says

Regan Jones, RDN, ACSM-CPT, host of This Unmillennial Life. "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,” according to Jones. 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, she says.

Jones agrees to stick to one cup. “Not only would more than one cup make someone jittery, but more importantly from a fasting standpoint, caffeine raises cortisol.” (Just a reminder, cortisol is the body’s stress hormone).

An increase in cortisol 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. One of the major benefits of fasting is keeping blood glucose and insulin low and [consuming] excess caffeine is in direct conflict with this goal,” states Jones.

Tea

Go for it. 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, says Palinski-Wade. 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,” she says.

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Water and seltzer

Drink up. Water is naturally calorie-free so there's no need to restrict it, says Palinski-Wade. 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 fruit wedges or 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, says Palinski-Wade. Carbonated water/seltzer can be treated in the same way as water, as long as it is naturally flavored and calorie-free.

Apple cider vinegar

Probably skip it. When it comes to fasting, many people think apple cider vinegar (ACV) or an apple cider vinegar tonic is okay to consume. According toJones, both ACV and bone broth have calories. "While minimal, the calories would ultimately lead to a metabolic breaking of the fast," says Jones.

However, if you really enjoy sipping ACV or an ACV tonic at other (non fasted) times, you're in luck. “If the goal is to simply reduce caloric intake overall throughout the day and give the body an extended period of digestive rest and lower insulin levels, I would say the ACV is less likely to raise insulin levels than bone broth.”

Bone broth

Not so fast. Unfortunately, if you enjoy sipping on a warm mug of bone broth, you may want to wait until after you have finished your fast. “Bone broth, while very popular in paleo and some fasting circles, can be a nutritious and satisfying beverage, but it can also be a source of protein. Protein raises blood glucose, which raises insulin levels," says Jones. While protein won't impact blood sugar and insulin levels as much as carbohydrate, it will still break your fast.

Soda

Skip it. If you're wondering if you can drink soda (or diet soda) while you're doing intermittent fasting, Palinski-Wade recommends staying away from soda in general, even if you’re not following a diet like intermittent fasting.

Regular sodas are usually loaded with sugar and calories and offer no nutritional value, she says. There also isn’t enough data and research to say whether diet soda is okay to drink during IF, but research suggests that consuming too many artificial sweeteners (as diet sodas tend to have) can increase cravings and appetite, as well as promote weight gain and the storage of fat.

“Your best bet is to limit all sodas as much as possible and satisfy carbonation cravings with seltzer or carbonated water,” she says.

Alcohol

Pass on it. Alcohol should never be consumed when in a fasting period, as its effects can be intensified when consumed on an empty stomach, says Palinski-Wade. Alcohol is also a source of calories, so drinking it would break your fast while also likely stimulating your appetite and leading to increased hunger and cravings.

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, says Palinski-Wade. 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. Palinski-Wade recommends taking a high-quality multivitamin daily when following any IF plan.

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

The bottom line: 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.

Emilia Benton is a Houston-based freelance writer and editor. In addition to Women's Health, she has contributed health, fitness and wellness content to Runner's World, SELF, Prevention, Healthline, and POPSUGAR, among other publications. She is also a 10-time marathoner, frequent traveler and avid amateur baker.

Ashley Martens is a Wellness Writer based in Chicago, Illinois. With a digital marketing background and her knowledge of general nutrition and a lifelong passion for all things health and wellness, Ashley covers topics that can help people live happier and healthier lives. 

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