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Home arrow Nutrition arrow Intermittent Fasting arrow Do BCAAs Break a Fast? What Science Says

Do BCAAs Break a Fast? What Science Says

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 22, 2023
3 min read 1495 Views 0 Comments
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When it comes to fasting, there are many misconceptions and uncertainties surrounding what is and isn’t allowed during this time. Is BCAAs safe to use while fasting or maybe it is best to leave this supplement for your eating window?

Do BCAAs break a fast

Many people wonder with intermittent fasting: what exactly will break a fast? If you have ever found yourself searching up every ingredient you want to consume, trying to figure out if you can have it during a fast, then this article is for you.

One common question that arises is whether branched-chain amino acids, or BCAAs, can be consumed without breaking a fast.

In this article, we’ll explore the science behind BCAAs and fasting, and whether taking BCAAs during a fast can be beneficial or detrimental to your overall health goals.

Do BCAAs Break a Fast?

The answer is complicated. Yes, consuming BCAAs is technically breaking your fast. However, using these supplements won’t diminish any of the potential health benefits of fasting.

If you’re dedicated to longer fasting periods for example that continue from 24 to 36 hours, you want to reduce the consumption of anything that could potentially break the intermittent fasting protocol.

To avoid breaking a fast, you want to avoid what is known as an insulin spike and avoid anything of caloric value. When taking BCAAs, you are causing an insulin response in your body. But, this insulin response is not considered a “spike.”

The insulin response caused by BCAAs isn’t enough to kick your body out of any potential fat-burning state that it has entered. So, we can confidently say that BCAAs do not break a fast in the long run.

What Are BCAAs?

BCAA is a general term for branched-chain amino acids, known as valine, leucine, and isoleucine. They are absorbed by the body and used as a source of energy for your muscles.

There are 20 different amino acids in the body, and they make up thousands upon thousands of different proteins that our bodies need to survive. However, only 9 of these amino acids are considered “essential” as the body cannot produce them independently. Therefore, BCAAs must come from the food we eat or BCAA supplements.

Does Glutamine Break a Fast?

Studies have found that glutamine does cause enough of an insulin response to breaking a fast when it comes to breaking a fast.

Glutamine is another amino acid. While it is naturally produced in the body, we often need more of it than is produced. Glutamine can also be found in food and supplements.

As far as fasting for gut rest goes, glutamine also stimulates the digestive tract, which means that it can break this type of fast.

Does Glycine Break a Fast?

If you’re looking to take pre-workout supplements during your fasting window, glycine is safe for fasting. Just be careful with how much you take – some studies suggest that glycine can inhibit autophagy.

Glycine is another amino acid often found in creatine and other pre-workout supplements. The primary function of glycine is to help supply energy to different parts of your body.

What Are the Benefits of BCAAs?

So, if BCAAs don’t break intermittent fasting, what are the main benefits of these amino acids? Let’s take a look at some of the health benefits of BCAA supplements.

#1 Helps to recover faster

When doing exercise or physical activity, BCAAs are known for helping prevent muscle breakdown and reducing muscle soreness and muscle fatigue.

These things will help you recover faster in terms of exercise to hit the gym again without as much physical or mental fatigue.

#2 Increases muscle mass

Most people use BCAAs to help increase muscle growth and muscle mass. It helps encourage the protein synthesis that is used in making more muscles.

One study showed that people who took BCAAs had a 22% increase in muscle protein synthesis compared to those who didn’t take it.

#3 Improves performance

This supplement can help you recover from intense workouts and help prevent muscle damage and support muscle growth. It’s easy to see how they also help improve your physical performance. They also help with brain function and even reduce mental stress.

#4 May help to lose weight

Some studies show that taking a BCAA supplement can help with weight management and encourage weight loss.

This works side by side with helping burn fat and reducing fat stores while encouraging muscle recovery and muscle gain.

A Word From Our RD

Intermittent fasting works by using fat reserves and encouraging your body to use those as energy during your fasting periods.

This system helps you lose weight and other health benefits: reduce insulin resistance, improve insulin sensitivity, lower blood pressure, and control your blood sugar.

BCAAs are excellent for either taking with supplements or consuming through certain foods. Of course, if you’re going to be taking them during intermittent fasting, you want to make sure that you’re just taking the supplements during your fasting window.

Otherwise, these amino acids offer a wide variety of health benefits. While they shouldn’t cause any problems, you should always seek professional medical advice before starting a new supplement.

For the most part, proper protein intake should help get you the right amount of BCAA intake, too. But if you find that you’re not getting the same benefits as others, you may require some kind of supplement in powder form that you can take with water or a smoothie.


So, do BCAAs break intermittent fasting? Thankfully, the answer is no. 

While these BCAAs can cause a slight increase in insulin levels, it is nothing close to an insulin spike that would kick you out of the fat-burning state that our bodies enter during intermittent fasting.

Consider doing so just before a workout when you prepare to take your branched-chain amino acid supplement. This will help you increase recovery time, improve your muscle building, and may even help you lose weight.

The health benefits of BCAAs are phenomenal and can even improve how you feel during those long intermittent fasting hours.

Whether you get enough during your eating window or need some supplements during your fast, BCAAs are safe for intermittent fasting.

To learn more about intermittent fasting and its facts click here.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 22, 2023
3 min read 1495 Views 0 Comments

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