Kristi Storoschuk, BSc (Hons.) is a science communicator with a research focus on ketogenic diets, metabolic therapies, and fasting for health optimization. She currently works alongside the world’s leading ketogenic researchers providing scientific education for the mainstream audience. Outside of her research, you will find her traveling the world, doing CrossFit, and optimizing her health through diet and lifestyle.

Staying hydrated while fasting is important, but it can be confusing which beverages do or don’t break a fast.

First and foremost, if a beverage contains calories, it technically breaks a fast. When we are in a fasted state, our body breaks down its energy reserves (glycogen and fat). So, it makes sense that when we add additional energy (Calories) to the system, this interrupts fasting metabolism and associated benefits we desire. Ultimately, consuming any Caloric beverage during a fast runs the risk of sending “fed” signals to our metabolism, and thus negating some of the benefits of a fast.  

That said, if you are fasting to induce a Caloric deficit for weight loss, a small amount of Calories, say 10-20 Calories from a splash of cream in your coffee, will not have a dramatic impact on your goals. 

Ultimately, to maximize the benefits of a fast, the closer you are to zero-Calorie beverages while fasting, the better. Opt for water (flat, mineral, sparkling, etc.) as often as you can, but there are plenty of non-Caloric beverage options if you want some occasional variety. These include black coffee and tea, lemon water, apple cider vinegar, and beverages containing non-nutritive sweeteners such as stevia and xylitol (check out our article on which sweeteners break your fast to learn more). 

Dr. Peter Attia, MD says “major in the majors, and minor in the minors.” This is sound advice when deciding for yourself which low- to non-Caloric beverages may interfere with your fast. Although specific to coffee, we recommend you check out the full video to learn about when you may or may not want to include coffee while fasting.

Some beverages might actually aid your fast, specifically, those containing electrolytes; just make sure to read the labels to make sure they have zero calories! Most electrolyte “sports drinks” are also sugar bombs. The beverages you absolutely want to avoid on a fast are alcoholic beverages (wine, spirits, liquor, beer, etc.), sugar-sweetened beverages, fruit juices, significant amounts of dairy and nut milks, and any other beverage with a significant Calorie count.

Thanks to Sherry H., Rebecca P., Beth AF., Lexi G., Jennifer M., Jeff E., Sandi C., Helen W., Belinda S., Heba M., Sunanda K., Nada M., Melissa G., Jessica S., Denis B., Alexandra M., Tony DB., Lauren A., Paulo NB., Tamara H., Agata N., Gigi D., David F., Pilar R., Mark M., Sharon K., and Sumeyye T. for submitting similar questions! 

What Drinks Break a Fast?

Thanks to Louise W. for this question.

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