Many people begin an intermittent fasting regimen with a specific goal in mind, like weight loss or improved gut health, while others may be seeking a whole new lifestyle and potential health benefits that may come with it.[1-3] Regardless of the reason behind it, an intermittent fasting schedule must adhere to stringent periods of eating and non-eating in order to be most effective.

This means that you don’t want to break your fast too soon, so as not to interrupt your schedule or minimize potential benefits of a fast. To maintain your fasting periods as much as possible, it’s important to understand what foods are more likely to break your fast and which don’t appear to have much impact.

Reasons Not to Break a Fast

While there are several ways to approach a fasting regimen, all schedules will incorporate structured fasting and eating periods. During fasting periods, your body undergoes what’s often called a metabolic switch, in which it starts burning fat for fuel instead of glucose. In essence, intermittent fasting is training your body to run primarily on fat stores instead of carbohydrates from recent meals, during specified times.[4]

The main reason to avoid breaking your fast during scheduled non-eating periods is that consuming carbs will switch your body back into using glucose for its main fuel source earlier than you had planned. Interrupting your fast early could throw off your intended schedule and minimize potential benefits.

Foods Allowed While Fasting

Even though fasting periods mean that you’re refraining from eating food, you may be able to consume certain foods and beverages without interrupting your fast. Rather than abstaining from food completely, some choose to practice “fat fasting” where their main goal is to remain in ketosis.

In fact, some fasting experts say that you can maintain ketosis as long as you don’t consume more than 50 grams of carbs during a fasting period. In other words, items that won’t switch your body back to utilizing glucose can be incorporated.[5]

This can be attractive especially if you find yourself hungry and needing something to help get you through to the next eating period. The question then becomes, what foods and drinks are appropriate in such a strictly low-carb window?

Always ask:  Will this break my fast?

Some things you could consume during a non-eating period without breaking your fast include the following:

• Water, whether it’s plain, carbonated, or naturally flavored with a few slices of cucumber or citrus wedges. You can also add electrolyte tabs.
• Bone broth, which can provide flavor as well as some nutrients and electrolytes, with few calories.
• Tea, without added sugar, honey, or milk.
• Coffee, without added sugar, flavoring syrups, or creamer.
• Small amounts of certain fats, such as MCT or coconut oil as these can curb hunger and maintain ketosis while helping stave off hunger until you get to eat a meal.[5]

It’s important to stay hydrated during a fast, as your body is actually losing fluid and electrolytes while it burns glycogen stored in the liver. Water is the preferred source of fluid for overall health, but incorporating the fluids listed above can help prevent redundancy and may even provide some electrolytes. Most importantly, they are low-calorie or calorie-free.

A Few Tips for Breaking Your Fast

As a general rule if you’re fasting longer than 24 hours, you will need a refeeding period to ease your gut back into normal functioning, which is typically about half as long as the total fasting period.  Eating too much too soon, or choosing foods that may be harder to digest, can be problematic. Avoid starting with large portions or with foods that are particularly high in fat and fiber, or with high glycemic index meals. Once you’ve gently introduced foods back to your body, you can add more of your “normal” foods back as well.

Furthermore, even though intermittent fasting focuses more on your eating pattern than the foods you eat, it’s important to choose healthy, whole foods as much as possible. For example, legumes, berries, leafy greens, whole grains, nuts, seeds, and lean proteins like fish and soy can all fit well in an intermittent fasting schedule and provide essential nutrients.

Eating healthfully not only supports any health goals you may have, but is also easier on your digestive system when transitioning between eating and non-eating periods.

Healthy Foods to Break a Fast

Foods and drinks that contribute more carbs will likely switch your body back into using glucose instead of fat stores. It’s fair to assume that all other “normal” foods, like the ones below, are best saved for your designated eating periods.

Some examples of healthy food choices to break a fast with ease may include:

• Dried fruits, like dates, raisins, or apricots as these offer a decent source of carbohydrates in a small serving to ease the body our of fat-burning.
• Smoothies, as these break down the fiber found in whole fruits and veggies but still incorporate vitamins and minerals and are easy to drink
• Soups made with broth and simple ingredients like tofu, beans, and softened veggies
• Cooked vegetables
• Berries
• Fermented foods like yogurt, kefir, tempeh, miso, or natto
• Eggs and fish
• Toast with avocado or nut butter

Of course, it’s helpful to experiment with your personal regimen to determine which foods you tolerate best when eating to break your fast. You can find some ideas here.

What About Supplements?

While it’s unlikely that you will experience nutrient deficiencies even during intermittent fasting, it depends on what you’re eating. Some people choose to continue taking supplements while practicing fasting, in effort to support general health and nutrition.

Surprisingly, some supplements may actually break your fast, and should therefore be avoided during non-eating periods. These include those that include added sugar, such as some gummies, as well as protein powders, which contain calories, amino acids and other nutrients that trigger an insulin response in your body.[6]

Other supplements without added sugar contain fewer carbs and are less likely to break a fast. For example, multivitamins without sweeteners, omega-3 supplements like fish, krill, or algae oil, calorie-free creatine powders, probiotics, or individual micronutrients that don’t contain added sugars. Keep in mind that if you supplement with fat-soluble vitamins A, D, E, and K, these are best taken during eating periods as they need dietary fat for optimal absorption.

In order to optimize your fasting period, ideally you want to stay away from foods with calories, but instead focus on remaining hydrated. Following the “rules” will help you get the most out of your fasting period.