Does Diet Coke break a fast? — Explained by Simple

Written by Melissa Renae

Medically reviewed by Louise Bula, RD

Published on January 29, 2024 | Updated on June 14, 2024

There’s just something about Diet Coke … believe us, we get it. But now, you’re making some changes — exercising a little more, trying intermittent fasting, drinking more and more water — whew, so much water. You gave up your precious Diet Coke, but you’re wondering if you had to. Will Diet Coke break my fast? Is it possible for that sweet and spicy sip to continue being a part of your routine? You need to know, does Diet Coke break a fast? 

Here at Simple, we have many resources to help you be confident in your intermittent fasting prowess, including “What to eat during intermittent fasting” and “What breaks a fast,” to name a few. 

Before we get to whether or not Diet Coke fits on the latter list, pop on over to take our Simple quiz and get started on your personal plan of action, but only if you don’t fit into one of these categories:

People who

• are pregnant, breastfeeding, or trying to conceive
• are living with type 1 diabetes
• are on prescription medications 
• are under the age of 18 or 80 years or older 
• are extremely active
• have a body mass index (BMI) < 18.5
• have an eating disorder or a history of one (or are at risk of developing one)

Sorry for that little detour, but it was important. To be on the safe side, we had to make sure you know who we do not recommend to embark on this fasting journey. 

 Now, let’s get back to answering your question: can you drink Diet Coke while intermittent fasting?

What is Diet Coke? 

Just in case it wasn’t your love for Diet Coke that brought you here, and you don’t know what we’re talking about, Diet Coke is the artificially sweetened, calorie-free version of The Coca-Cola Company’s classic cola-flavored beverage. 

Nutritional value

Diet Coke’s claim to fame is not its nutritional value; really, it’s the lack thereof. It’s sugar-free with zero calories and made of carbonated water, caramel coloring, artificial sweeteners, natural flavors, caffeine, and preservatives. It’s meant to have the same flavor as the original but be an alternative choice for the calorie- or sugar-conscious consumer. But does this make Diet Coke and intermittent fasting a winning duo? 

Will Diet Coke break a fast?

With no calories or sugar to trigger an insulin response, a diet soda does not break a fast, and that includes Diet Coke. That’s right, you can have Diet Coke while intermittent fasting. You can even include Diet Coke in your fasting window while keeping your fasting intact! 

Health benefits and possible drawbacks of drinking Diet Coke while intermittent fasting

Benefits

• Satisfy cravings — Diet Coke can add a little buffer, especially for those transition days early in your fasting journey that can be a little rough. Drinking Diet Coke during intermittent fasting can help you stick to your calorie deficit goals by satisfying your sweet tooth.

• Aids in weight loss — Diet soda intake in moderation has been shown to help maintain a calorie deficit, ultimately aiding in weight loss for those with a higher BMI or who are at risk for diabetes.[1] 

Drawbacks

• Does not replace water — Although intermittent fasting and Diet Coke do play well together, water is still the gold standard for hydration. Make water your go-to with Diet Coke as an occasional alternative. 

• May cause insulin resistance — While intermittent fasting and insulin resistance have a positive relationship, there is some research that suggests consuming artificial sweeteners may alter the gut microbiome, worsening glucose response and making weight gain a possible risk.[2] While Diet Coke won’t break a fast, it could complicate the relationship between intermittent fasting and blood sugar. More research is needed, however. 

• May erode teeth — A high intake of diet drinks can cause teeth enamel to erode.[3] It is caused by the acidic ingredients in diet beverages. 

Tips on drinking Diet Coke during a fast

The main tip for including Diet Coke during intermittent fasting is to drink it in moderation. Intermittent fasting is all about flexibility. Knowing what you can drink while fasting is a small part of the fasting success equation. As long as you keep your intake balanced with a variety of health-promoting foods, you can keep your Diet Coke, and you will still see benefits from your efforts. 

Written by Melissa Renae

Medically reviewed by Louise Bula, RD

Published on | Updated on June 14, 2024