Ask the online dietitian: what can you drink during intermittent fasting?

Hello! If this is your first blog post of mine, welcome. You’re just in time because I’m about to shift how I share blog posts.

Starting this week, I am going to transform the traditional blog style into a weekly question and answer format. I receive so many great questions each week on the Revolution Dietitian Facebook community and Instagram. It surprises me when I hear that everyone thinks they are alone, or perhaps the only one with a question.

I’m here to tell you that you aren’t alone! We’re here to figure this out together.

Let’s get right to the most frequently asked question I receive about intermittent fasting.

What can you drink during intermittent fasting?

All Types of Water

Plain water. Sparkling water. Seltzer water. Mineral water. Flavored water. All of these are preferable choices during your fasting window.

A word of caution about some flavored waters is that they can contain added sweeteners, such as sucralose or acesulfame-K. Depending on the individual, the sweet taste of these two sweeteners could trigger an insulin response, which is not preferable during a fast.

Lemon water

Water with lemon slices is fine during a fast. The calories in the lemon, or other citrus fruit, is negligible and not enough to break a fast.


Unless you are going for a pristine water fast, black coffee is okay during your intermittent fasting window. The caffeine in coffee does elicit a metabolic response, but the calories in coffee are very low.

Coffee also contains chlorogenic acid, an enzyme that is associated with fat burning. I would like to add a word of caution because the acid in coffee might be difficult to digest on an empty stomach for conditions such as acid reflux.

Coffee with cream

Does coffee break a fast for gut rest or as part of a water-only fast? Yes.

Fasting for weight loss, metabolic health, longevity? No.

Hooray! Coffee and cream is okay. Now, let’s define how much cream or milk you can have and still be considered “fasting.” One tablespoon is quite different from a quarter cup.

There is no scientific evidence to support this theory, but there is advice “out there” saying that if you consume less than 50 calories, it won’t break your fast. I suspect this is loosely derived from the fact that a low calorie food is defined by the FDA as having less than 40 calories per serving. Plus, 50 calories is a negligible amount and won’t have a significant effect on total calorie consumption or negatively impact the beneficial effects of fasting.

All that considered, 1-2 tablespoons of cream in your coffee is just fine during a fast. Or if it helps to remember 50 calories or less, which is about the caloric equivalent of 1-2 tablespoons of creamer, choose what works best for you.

What about sweeteners?

If you put sugar in your coffee, the fast is broken. Most non-nutritive sweeteners like monk fruit, erythritol, xylitol are not problematic.

In some people, the sweet taste of stevia and Sucralose is enough to trigger insulin release (this is known as cephalic phase insulin release). Without a blood sugar monitor, there really isn’t an accurate was to tell if this is affecting you.

If you are drinking many beverages sweetened with stevia or Sucralose and find that you are still struggling with weight loss, then it might be an indicator that you are experiencing additional insulin production.


It’s not the tea, it’s what you put in it that matters.

Green Tea

Though it does contain caffeine, green tea is fine to consume during a fast. Similar to coffee, I would caution against drinking green tea in the afternoon, as the caffeine could interfere with sleep.

Herbal Tea

Many people find as they shift their evening glass of wine to dinnertime to close their eating window that they are still searching for a beverage to enjoy while they watch tv or relax. Herbal tea, such as chamomile, mint or any caffeine-free tea would be a good option after dinner.

There is your quick summary to answer the question “what can you drink during intermittent fasting?”.

My hope is that you will continue to send me your questions and we can make this weekly blog post a place for you to find helpful guidance and actionable advice.

Cheering for you,


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Hi, I'm Shannan.

I help adults make confident choices for a lifetime of good health.


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