Does Oat Milk Break a Fast? (The Rule For Intermittent Fasting)

Written by: Jeana Marie

Fasting, including intermittent fasting, has become an increasingly popular way for people to lose weight and improve their health. If you practice fasting, it’s helpful to know what, if anything, you can consume without breaking your fast. 

If you are a fan of oat milk, you may wonder if having a bit in your coffee or tea will break your streak during fasting. 

While technically consuming any foods or beverages other than water, tea, or coffee, can be considered breaking a fast, the answer depends on your goals, fasting guidelines, and how much oat milk you consume. 

What Qualifies as Breaking a Fast?

Does consuming oat milk break a fast?

To answer the question, it’s helpful to understand what it means to break a fast. What constitutes breaking your fast depends on your specific goals and restrictions for the fast. 

For some, consuming anything besides water is breaking their fast. 

For others, eating food outside their intermittent fasting window breaks their fast.

For example, eating fish on Friday during Lent is allowed for Catholics, but eating another type of meat would break the fast. 

Generally, breaking a fast involves consuming calories or nutrients that stimulate your digestive system and cause your blood sugar levels to rise.

This can include juice, plant-based milk, creamer, and broth, depending on the parameters of your fast.

Check out this video from Dr. Becky Gillaspy for more info on what breaks a fast.

Can You Drink Oat Milk While Fasting?

Oat milk is a widely used alternative milk with a creamy texture and milk taste.

However, because it’s made by blending whole oats with water, it has more carbohydrates than most plant-based milk, even without added ingredients. 

Per 8-ounce serving, unsweetened oat milk contains:

  • 80 calories
  • 1.5 g fat
  • 160 mg of sodium
  • 14 g carbohydrates
  • 2 g fiber
  • 1 g sugar

This nutritional profile belongs to Willa’s Kitchen Oat Milk, which has one of the lowest carbohydrate and sugar counts of any oat milk brand on the market. 

Most oat milk contains even more sugar, typically around 7 grams of added sugar.

chobani oat milk added sugar

This is because oats contain a natural sugar called maltose, which the body processes like added sugars.

This is especially true for brands like Oatly that use enzymes during processing to break down the oats to make their product creamier. 

Some oat milk varieties add sugar, such as cane sugar, to sweeten their product, resulting in an even higher carbohydrate/sugar amount. 

Why Does This Matter for Fasting? 

Maltose has a high glycemic index of 105.

According to the Harvard School of Public Health, high glycemic foods, rated between 70 and 100, can cause your blood sugar to spike. 

While oats in raw form might reduce this blood sugar response due to their high fiber content, most oat milk isn’t high in fiber since the hulls are strained out to make the product smoother. 

This means that if you were to drink a glass of oat milk during a fast, you’d most certainly be breaking the fast by causing your blood sugar to rise.

This would stimulate insulin production and activate your digestive system. 

What if You Only Drink a Small Amount of Oat Milk?

What if you only drink a few teaspoons of oat milk or put a splash in your coffee or tea?

For example, if you consumed 4 ounces of oat milk, you’d get around 40 calories and 7 grams of carbohydrates. 

Although there is no hard rule, most guidelines for fasting require you to stay under 50 calories not to break your fast. 

However, some sources advise staying under 1 gram of carbohydrates to avoid breaking the fast and kicking your body out of autophagy. 

As a final conclusion - yes, consuming oat milk will break a fast - however, if you drink an unsweetened version and do a bit of carbohydrate counting, you can enjoy a few tablespoons without going over these fasting guidelines. 

Here’s what you need to know: 

  • Number of carbohydrates per serving
  • Serving size in ounces 
  • 1 ounce = 2 Tablespoons

Once you have these numbers, you can figure out how much oat milk you can have to stay under 1 gram of carbohydrates and not break your fast. 

The following table provides a breakdown of a few unsweetened oat milk brands and how much you could drink without breaking your fast:

Oat milk

Carbs per serving

Carbs per tablespoon

Amount to consume without breaking a fast













What is Fasting?

As a spiritual and healing practice, fasting has been used for centuries.

Fasting involves abstaining from food and drink for specific periods, typically several hours to days.

For religious purposes, fasting is used as a form of spiritual purification.

For example, Catholics abstain from meat each Friday during Lent, and Muslims fast from sunup to sundown during Ramadan. 

Fasting has also been used to heal the body.

In Ancient Greece, Hippocrates used fasting to treat digestive issues and fevers. He believed it allowed the body to cleanse and heal itself.

Traditional Chinese medicine uses fasting as a therapeutic tool, and Ayurveda, an Indian system of medicine that is thousands of years old, uses fasting to promote health and well-being.

In the 20th century, fasting was used by Dr. Frederick Banting, one of the co-discoverers of insulin, to help patients manage diabetes.

He found that short periods of fasting helped his patients lower their blood sugar levels and improved their insulin sensitivity. 

Here's a great video that goes even more in depth into the history of fasting.

Modern Fasting Practices

In the modern world, fasting is still used to get the body back on track, heal, and potentially lose weight.

Recent interestest has prompted new research into the benefits of fasting, which has shown that the practice can help the body in several ways. 

In general, fasting can:

  • Increase fat-burning and weight loss
  • Improve insulin sensitivity
  • Lower blood pressure
  • Improve mental clarity
  • Reduce inflammation
  • Increase longevity

A 2022 study found that intermittent fasting (IF) results in a condition called autophagy.

This is a complex biological process in which human cells effectively destroy or get rid of damaged cells.

Cleveland Clinic describes it as a “recycling system” for your body, where cells disassemble broken parts and resume bits that work, reducing cellular-level clutter in your body. 

Another 2022 study reported that fasting, specifically IF, helps with weight loss, energy production, and improvement in circadian clocks.

This means that fasting can benefit your physical and mental health.

Intermittent Fasting

One of the most popular fasting methods today is intermittent fasting.

This practice involves abstaining or restricting your food intake for a specific hour interval each day. Several types of IF exist, including time-restricted feeding, alternate-day fasting, and the 5:2 diet. 

In time-restricted IF, you would limit your food intake to a specific window of time.

For example, fast for 16 hours, then eat all your allowed calories for the day within the remaining 8 hours. On the 5:2 diet, you would eat your normal calorie intake for 5 days a week, restricting your calories to around 500 to 600 on the remaining 2 days. 

Fasting on Keto

Keto is a popular diet that limits carb intake to around 20 to 50 carbs per day.

Many people on the keto diet practice some form of fasting because it can quickly move them into ketosis, which is the state where the body burns fat for energy instead of carbohydrates. 

Although fasting on keto isn’t much different from other types of fasting, the focus is on limiting carbohydrates specifically and maintaining ketosis rather than just calories or food intake. 

Juice or Water Fasting

Many people also practice water or juice fasting for various health benefits.

Water fasting involves abstaining from food or drink other than water for days or weeks.

It is one of the most intense forms of fasting and should not be practiced without the supervision of a physician. 

Similarly, juice fasting is a fasting method that involves only consuming fresh fruit and vegetables for a specific period.

People believe juice fasting gives the body the necessary minerals and vitamins and gives the digestive system a  break from processing heavy foods. 

Can You Eat or Drink Anything During a Fast?

There are many different types of fasting and goals for each fast. This makes it hard to know whether you can eat or drink anything during a fast, including oat milk. 

Most fasts allow limited consumption of the following:

  • Water - all fasts (except dry fasting, which is controversial and not recommended by most healthcare professionals) allow for water consumption. Water is essential for hydration and well-being, making it necessary during any fast. 
  • Tea and coffee - most fasts allow the consumption of tea and coffee without additives like creamer, milk, or sugar. Some fasts allow a small amount of these ingredients, while others restrict caffeine. 
  • Juice - most fasts don’t allow juice consumption; however, the juice fast relies solely on juice during the fasting period.
  • Broth - some diets allow a small amount of broth, which is made from simmering herbs, vegetables, and bones in water. Bone broth, for example, is high in nutrients but only has about 30 to 60 calories, making it acceptable to some people on a fast. 
  • Electrolytes - these essential minerals help regulate bodily functions like muscle and nerves, blood pressure, and fluid balance. Most fasts allow you to consume supplements that include electrolytes like sodium, potassium, and magnesium. 
  •  Alternative milk - some fasts allow a small amount of plant-based beverages, such as almond, oat, or soy milk. This depends on your fasting goals and whether the product has added sweeteners that may spike your blood sugar. 

Final Thoughts: Should You Drink Oat Milk When Fasting?

Fasting is not a one-size-fits-all approach to wellness. While yes, technically, drinking oat milk would break your fast if you consume a typical serving, you could still have a small amount. 

That being said, it's important to remember you should consult with a doctor or dietitian when considering fasting. It’s also important to listen to your body and give it the nutrients it needs, even if that means breaking a fast. 

If you drink oat milk during or when intentionally breaking your fast, opt for a brand with minimal added sugars and ingredients to help your body come out of its fasting state for a more smooth transition.

About the Author

Jeana Marie is a freelance digital content writer. Her writing focuses on mental health, self-improvement, and healthy living. When she's not writing, Jeana enjoys spending time with her daughters and discovering new coffee and herbal tea flavors.