What Foods Break a Fast?

You want to try intermittent fasting, but before you jump right in, you should know what foods break a fast.

Black coffee?

Coffee with cream?

Coffee with butter?

Today’s post is a follow up to last week’s article on using intermittent fasting for weight loss. “What breaks a fast?” is the most commonly asked question I get. For good reason because depending on who you ask, you’ll get a wide range of answers on this.

The most important factor to keep in mind is your goal. Ask yourself, am I looking for a pristine fast that fully rests my gut and cells? Or am I looking for an eating window during the day that helps me set boundaries around food?

What does breaking a fast mean?

If you are doing an overnight fast, the first food or beverage that supplies you with calories technically breaks the fast. Calories in, fast broken. Black and white.

Where this topic starts to get grey is what foods bring you out of a fasted state.

Quick primer on fasted states

A fasted state generally refers to nutritional ketosis, which occurs on an extremely low carbohydrate diet (i.e. ketogenic diet) or during a prolonged fast (>24 hours).

There are foods that will break a fast, meaning they will give you calories, but not take you out of ketosis.

Nutritional ketosis is a delicate balance. Too many calories will take you out of ketosis. Likewise, additional carbohydrates or protein will take you out of ketosis.

Here’s the thing, you’re not in a state of nutritional ketosis from an overnight fast. I’m not either, so this isn’t a judgement.

What is more important is asking yourself this one question below.

Why am I doing a fast?

You have to start with this question because that will tell you the answer to what will break your fast.

For longevity and weight loss, the rules are less stringent than if you are going for metabolic rest.

If you want to do a pristine overnight fast or want a fast that promotes optimal cellular health and gut rest, then water-only fasting is your best choice.

Water-Only Fasting

This is a purist approach to fasting. The intention here is to eliminate anything with calories or substances, such as caffeine that would stimulate metabolism.

Water-only fasting is for complete metabolic, or cellular rest or complete gut rest.

You can use water-only fasting for a nightly fast or for a prolonged fast, which I consider anything over 24 hours. Be sure to consult your physician before attempting any kind of prolonged fast.

What Foods Break a Water-Only Fast

Any food or beverage with calories, including black coffee will technically break a water-only fast.

But black coffee won’t bring you out of a fasted state and has been associated with enhancing some of the benefits of fasting. Sigh…it would be much easier to explain if there were a simple answer.

Exceptions to Water-Only Fast

If the thought of nothing but water is a mental block, there are a few exceptions to this rule. Flavored and sparkling waters are generally fine during a water-only fasting period.

A slice of lemon in water and caffeine-free herbal tea are also acceptable.

Intermittent Fasting

There is a lot more flexibility with intermittent fasting because there are many different ways you can approach fasting. I like to focus instead on a daily eating window.

Will this Break an Intermittent Fast?

Black Coffee (No) contains 5 calories per cup, is okay during a fast and will not take you out of fasted state. I do not consider drinking black coffee as breaking a fast.

Coffee + Cream (Yes) technically breaks a fast. Here’s why it doesn’t really matter.

If you are only putting 2 tablespoons of half and half in your coffee, that will give you about 45 calories, including calories in the coffee itself.

Does coffee with cream break a fast? In my opinion, yes.

Is it enough to hinder any weight loss or metabolic health benefits from regularly compressing your calories into a smaller eating window? probably not. There isn’t scientific data to suggest that it does or doesn’t.

So, can you have coffee and cream to help you meet your eating window goals? Of course.

But, are you still fasting after you drink the coffee + cream? No. Does that really matter…probably not.

Tea (No) contains very little calories and can be part of your fasting window intake.

Lemon Juice (No) unless you are going overboard with the lemons, you are getting negligible amounts of calories.

Apple Cider Vinegar (No) similar to lemon juice, ACV has a negligible amount of calories.

Bone Broth and Powdered Collagen (Yes) the calorie and protein content in the bone broth and collagen powder are significant enough to break the fast.

Butter, ghee or coconut oil. (Yes) if you are adding a tablespoon of butter, ghee or coconut oil to your coffee, that adds upwards of 100 calories and 10 grams of fat, so that for certain breaks a fast.

What does the data tell us?

The exciting and frustrating part about nutrition science is that it is always evolving.

My opinions reflect the literature that is available now. Many of the studies that were done are mice studies or examined effects on a cellular level, meaning in a test tube.

There isn’t enough data yet to provide definitive guidelines on what foods for certain can be a part of fasting.

This is where I take my expertise as a dietitian, examine the research that is out there and come up with solutions that fit my clients’ goals.

If you are trying this on your own, it may take some experimenting. Don’t forget to check with your physician before trying fasting and remember, the information in the blog is for educational purposes only and don’t constitute medical advice.

Zero Fasting has an interesting look at what breaks the fast on their blog, as well as this Healthline article which talks about supplements that could affect your fasted state.

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Hi, I'm Shannan.

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

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