What Can You Consume Whilst Fasting? Drinks, Food, And More

We'll Look At How Breaking A Fast Is Defined As Well As Which Foods, Drinks, And Supplements Are Permitted While Fasting

If you are in a position where you find yourself needing to lose weight, deciding what diet to follow can be one of the most difficult decisions. It seems simple enough: eat fewer calories, and you will lose weight. 

However, with the overwhelming plethora of popular diets to choose from, many people get “paralysis by analysis,” meaning that there are just so many options that they end up not being able to choose any diet and move forward with their weight loss plans.

Intermittent fasting is one of the more popular approaches to weight loss, and unlike many popular diets, with intermittent fasting, you don’t have to worry so much about what you can and cannot eat, but rather just when you can or cannot eat.

This can make intermittent fasting appealing to people who don’t want to give up certain foods or food groups altogether. When it’s time to eat, you can enjoy the foods you like in moderation.

However, what can you drink during fasting itself? And what foods can you have while intermittent fasting to get through the fast? You may be surprised to learn that even some supplements can technically break your fast.

Hence, this article will shed light on exactly what you can and cannot eat, drink, or consume during intermittent fasting.

Let’s get started!

A person holding out a glass of water.

What Is Intermittent Fasting?

Intermittent fasting is a broad term to describe a type of diet that is defined not by what you can and cannot eat but by when you can and cannot eat.

There are many different approaches to intermittent fasting schedules, some of which involve restricting the window of time that you can eat in a day (time-restricted eating intermittent fasting), whereas others involve fasting or severely restricting caloric intake every other day (alternate day intermittent fasting).

With any intermittent fasting schedule, only water, black coffee, unsweetened tea, and other calorie-free beverages are permitted during the fasting window. You cannot consume any food or caloric beverages.

As mentioned, there are no rules about what you can eat when it is time for you to eat, but as with any diet, the goal should be to try to consume nourishing foods in a well-balanced, healthy diet.

Intermittent fasting is a popular dietary approach for weight loss, but there can be other potential health benefits —such as decreased inflammation, improved cellular health by way of increased autophagy, and improvements in cardiovascular health—which spur some people to take this approach to their dietary habits.1Aksungar, F. B., Topkaya, A. E., & Akyildiz, M. (2007). Interleukin-6, C-reactive protein and biochemical parameters during prolonged intermittent fasting. Annals of Nutrition & Metabolism51(1), 88–95. https://doi.org/10.1159/000100954Goodrick, C. L., Ingram, D. K., Reynolds, M. A., Freeman, J. R., & Cider, N. L. (1982). Effects of intermittent feeding upon growth and life span in rats. Gerontology28(4), 233–241. https://doi.org/10.1159/000212538Cienfuegos, S., Gabel, K., Kalam, F., Ezpeleta, M., Wiseman, E., Pavlou, V., Lin, S., Oliveira, M. L., & Varady, K. A. (2020). Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metabolism32(3), 366-378.e3. https://doi.org/10.1016/j.cmet.2020.06.018

What Counts As Breaking A Fast?

Technically, consuming any food or drink containing calories will break a fast.

However, consuming small amounts of calories will not necessarily stop the benefits of ketosis.

On the other hand, consuming small amounts of calories may still reduce some of the cell maintenance benefits of autophagy.2Parzych, K. R., & Klionsky, D. J. (2014). An Overview of Autophagy: Morphology, Mechanism, and Regulation. Antioxidants & Redox Signaling20(3), 460–473. https://doi.org/10.1089/ars.2013.5371

The takeaway?

If you are fasting for autophagy, you should aim for zero calories or as close to zero calories as possible.

Even black coffee or herbal teas without any additives contain tiny amounts of calories, yet, small amounts such as this are probably OK to consume whilst fasting. The trick is to consume as close to zero calories as possible.

If you are fasting for weight loss, it may be OK to consume a few calories and still retain most of the weight-loss benefits.

Recommended: The 10 Best Foods To Break A Fast With

A cup of tea being poured.

What Can You Drink During Fasting?

Now let’s get into a bit more detail about what to drink during intermittent fasting.

Firstly, you can drink plain water or unsweetened carbonated water during a fast. In fact, it is very important to keep drinking water during a fast to stay hydrated.

While fasting, you can also drink non-caloric beverages like unsweetened herbal or green tea, club soda, or seltzer.

Unsweetened electrolyte tablets or powders are also recommended. The sodium can help you feel fuller and will prevent electrolyte imbalances.

Lemon water without any added sugar is also unlikely to break your fast, although you should make sure to drink it with lots of water, not drink it in excess, and watch out for acidity, which may be more pronounced on an empty stomach.

Other flavored waters can be OK to drink if they don’t contain calories.

Some individuals find a small amount of apple cider vinegar mixed with water can also be an effective fasting drink to stave off cravings.

A glass of water with a spoonful of electrolyte powder next to it.

Black coffee is also technically permitted during an intermittent fasting diet because the caloric content is so small that it is not thought to induce metabolic changes that take you out of the fasting state.3van Dam, R. M., Pasman, W. J., & Verhoef, P. (2004). Effects of Coffee Consumption on Fasting Blood Glucose and Insulin Concentrations: Randomized controlled trials in healthy volunteers. Diabetes Care27(12), 2990–2992. https://doi.org/10.2337/diacare.27.12.2990

One cup (240 ml) of black coffee only contains about 3 calories, along with just trace amounts of protein, fat, and minerals, so it is probably OK to drink, even if you are fasting just for autophagy.4Pietrocola, F., Malik, S. A., Mariño, G., Vacchelli, E., Senovilla, L., chaba, kariman, Niso-Santano, M., Maiuri, M. C., Madeo, F., & Kroemer, G. (2014). Coffee induces autophagy in vivo. Cell Cycle13(12), 1987–1994. https://doi.org/10.4161/cc.28929

However, to not break your fast it should stay as black coffee, without any added sugar, sweetener, dairy, or creamer.

Additionally, you can drink non-caloric beverages during fasting.

Remember, you need to make your diet work for you. Having a few calories while intermittent fasting shouldn’t sabotage your results and may help you get through the fast.

A person drinking a glass of water.

What Can You Not Drink During Fasting

To not break your fast, you should avoid drinks containing dairy, glucose, other sugars, alcohol, or other sources of calories. Even diet sodas with artificial sweeteners are not recommended as they can still make your insulin levels spike and blood pressure rise, reducing the benefits of fasting.

If it contains calories or carbs – it will technically break your fast and can increase blood sugar levels.

However, as mentioned above, you need to make it work for you, and if you find that consuming small amounts of calories gets you through the fast then there is nothing wrong with that, and benefits from fasting will still be achieved.

What Can You Eat During Fasting?

It may sound like an odd question—what can you eat during fasting? After all, by definition, fasting technically involves abstaining from consuming all caloric food or beverages.

Technically, you cannot eat anything during intermittent fasting when you are outside of your eating window, as any caloric foods will likely take you out of the fasted state.

However, it is important to note that whenever you take on any diet or a dietary approach, including intermittent fasting or water fasting—whether a time-restricted intermittent fasting diet like 16/8 intermittent fasting or multi-day water fast—you need to make the diet work for you.

There are no laws against adjusting or modifying diet rules to make the diet more feasible or healthier for you.

So, for example, even though you aren’t technically supposed to eat or drink anything that contains calories while fasting, if you need to have a small number of calories spaced out during the fast to help you get through, that is fine.

A cup of black coffee.

There is very little research pointing to the specifics about how many calories you can eat to keep your body in a sustained fasting state, such that the amount of energy coming in is not enough to induce metabolic effects to switch “off” the benefits of fasting and start trying to use the calories you have consumed for energy.

Some intermittent fasting “experts” say that your body will remain in a fasted state as long as you stay under 50 calories. 

However, there isn’t much scientific evidence to necessarily substantiate this seemingly arbitrary number, nor is it particularly clear about the timeframe within which these 50 calories can be consumed. Is it 50 calories per hour? 50 calories per day? 

As can be seen, there is still a lot that we have yet to learn about intermittent fasting, the metabolic benefits of fasting, and the effects of eating a few calories while fasting.

Therefore, if you do feel strong cravings to drink or eat during intermittent fasting and you’re willing to give yourself some latitude on having a few calories, here are some ideas of what to eat during intermittent fasting. 

Again, keep in mind that eating during intermittent fasting isn’t technically permitted if you want to be strict with your fasting.

Overall, although you shouldn’t technically eat anything while fasting, having some very low-calorie foods during prolonged fasts can be a tenable option, especially for those new to fasting, and most of the fat-burning benefits are likely to be maintained. 

Basil leaves.

#1: Basil Leaves

Adding basil to your water or club soda can add flavor, or you can chew on the leaves if you feel like you really want to eat during intermittent fasting. A quarter cup of basil (about 10 leaves or 6 grams) contains only 1-2 calories, while a full cup contains about 6 calories.5{{MetaTags.title || “Nutritionix”}}. (n.d.). Www.nutritionix.com. Retrieved December 20, 2023, from https://www.nutritionix.com/food/fresh-basil/1-cup

#2: Parsley

Like basil, parsley is very low in calories. There are about 4 calories in 10 sprigs. You can chew on parsley or add it to water.6FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170416/nutrients

#3: Iceberg Lettuce

Nibbling on a little bit of iceberg lettuce may work if you’re willing to give yourself some latitude to consume a few calories while intermittent fasting and really want to eat.

One cup (57 grams) of iceberg lettuce provides only 8 calories, along with some vitamin A, vitamin K, and folate.7FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/169248/nutrients

#4: Watercress

Watercress is a super nutritious green leafy vegetable that contains only 4 calories per cup (34 grams). One cup also provides 120% of the daily value (DV) for vitamin A, 71% of the DV for vitamin K, and 16% of the DV for vitamin C.8FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170068/nutrients

Swiss chard leaves.

#5: Swiss Chard

Swiss chard is another nutritious dark, leafy green that is quite low in calories yet high in vitamins and minerals.

It is particularly high in vitamins A, C, and K, containing 249% of the DV of vitamin K per cup. Plus, one cup of chard (36 grams) provides only 7 calories.9National Institutes of Health. (2021, March 29). Office of Dietary Supplements – Vitamin K. Nih.gov. https://ods.od.nih.gov/factsheets/vitaminK-HealthProfessional/

Therefore, a few leaves of Swiss chard can be a reasonable thing to eat during intermittent fasting if your stomach is growling and you feel like you have to eat something.

#6: Radishes

Radishes are slightly higher in calories than lettuce, watercress, or herbs, but they contain only 19 calories per cup.10FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/169276/nutrients

Therefore, if you have just one or two every few hours, you will probably not take yourself out of the fasted state, and the crunch can be more satisfying and help you feel like you are eating during intermittent fasting – more so than having a few leaves of lettuce. 

You will also get potassium, folate, and vitamin C.

A stalk of celery, a bowl of celery and celery juice.

#7: Celery

Celery can be a good food to eat during intermittent fasting if you are permissive with yourself in terms of eating a few calories because it’s crunchy, contains fiber, and takes some time to eat, helping you feel like you were able to eat something.

One full cup of celery (120 grams) has only 19 calories, so if you have just a stalk or two periodically during a prolonged fast, it should not induce many metabolic changes that take you out of a fasted state.11FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/1103346/nutrients

#8: Cucumbers

Cucumbers are primarily water, so they are very low in calories. If you’re looking for something to drink during intermittent fasting periods, you can add cucumber slices to your water to add a bit of flavor and then suck on or eat the cucumbers afterward.

One half-cup serving of cucumbers (52 grams) has only 8 calories.12FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/168409/nutrients

#9: Broth

Clear soup stocks and broths can provide the sodium and electrolytes you need without many calories, making these liquids good foods to eat while fasting.

One bouillon cube contains about 11 calories.13FoodData Central. (n.d.). Fdc.nal.usda.gov. https://fdc.nal.usda.gov/fdc-app.html#/food-details/171562/nutrients

Broth is lower in carbohydrates and calories than stock, so it tends to be a better option for what to eat during fasting. Additionally, although bone broth is packed with nutrients, it is also higher in calories and will take you out of the fasted state.

With that said, bone broth is one of the best foods to eat to break a fast since it contains highly digestible collagen protein, tons of vitamins and minerals, and provides you with hydration.

A bowl of red jello.

#10: Sugar-Free Jello

Although certainly not nutritious and not recommended as part of a “healthy diet,” sugar-free jello can be an option for something to eat during fasting if you really need the sensation of eating something.

One serving (117 grams) provides about 23 calories.14{{MetaTags.title || “Nutritionix”}}. (n.d.). Www.nutritionix.com. Retrieved December 20, 2023, from https://www.nutritionix.com/i/nutritionix/sugar-free-jello-1-serving/55eefb6d44a4420f07f96055

However, keep in mind that you’ll get no nutritional value, and artificial colors and sweeteners are unhealthy. 

Therefore, if you are fasting to improve your health, it is not a good idea to indulge in sugar-free gelatin desserts while fasting.

Which Supplements Break A Fast?

Some people may choose to take supplements during fasting to try and keep their mineral and nutrient levels balanced. However, some supplements may break a fast.

Gummy multivitamins, branched-chain amino acids (BCAAs), protein powder, and supplements containing other ingredients such as maltodextrin, pectin, cane sugar, or fruit juice concentrate contain sugar, calories, or trigger an insulin response.

This means that they technically break your fast and reduce the beneficial effects of fasting on your insulin sensitivity.

Which Supplements Are OK To Take During A Fast?

To ensure your supplements don’t break a fast, make sure they contain no added sugar or digestible carbs.

Supplements such as omega-3 oil and collagen contain a few calories and may slightly affect autophagy, but aren’t likely to have a drastic impact on your fast.

Other supplements such as prebiotics or probiotics, creatine, micronutrients, multivitamins, or electrolytes are unlikely to break your fast.

However, it is important to take note of whether or not a supplement is recommended to be consumed with food or on an empty stomach before taking it during a fast, to avoid unwanted side effects.

If you would like to get more into the nitty gritty of intermittent fasting schedules, check out our article: The Complete Guide To Intermittent Fasting Schedules.

References

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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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