What Are BCAAs? An RD Explains | Garage Gym Reviews

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What are BCAAs? Branched-chain amino acid supplements, or BCAAs, are right up there with creatine in terms of popularity in the fitness community. Both are common ingredients in pre-workout and other dietary supplements that are intended to boost exercise performance and change body composition.

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However, what are these compounds exactly? Despite them being quite ubiquitous in the gym, few are aware of the full range of the benefits BCAAs can offer. Additionally, most people are also unaware of how overhyped many of these benefits are. So, let’s take a look at BCAAs, what they are, how they work, and whether they can really revolutionize your fitness goals.

Medical disclaimer: This article is intended for educational and informational purposes only. It is not intended as a substitute for medical advice. For health advice, contact a licensed healthcare provider.

What Are BCAAs?

As most of you have likely heard a million times, amino acids are known as the building blocks of muscle. You can’t build a house without bricks and the body cannot build muscle without amino acids. This is why a high-protein diet is such a huge part of the lives of bodybuilders, athletes, and fitness buffs.

There are nine essential amino acids (EAAs) in the body: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Non-essential amino acids can be created by the human body when needed. However, essential amino acids are so named because the body cannot make them, so they must be obtained from outside sources such as food or supplements.

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BCAAs or branched-chain amino acids are the essential amino acids leucine, lysine, and valine and they are called “branched-chain” simply because of the appearance of their chemical structure. So, what makes them so special compared to the other essential amino acids?

How Do BCAAs Work?

Compared to the non-essential and other essential amino acids, BCAAs are some of the most abundant amino acids in your muscle tissue. Thus, according to the Journal of Nutrition¹, they are mostly metabolized in the muscle rather than the liver, where the other amino acids are processed.

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This is why they are thought to improve exercise performance and stimulate muscle protein synthesis. Each amino acid plays its own role in the body, with some being more impactful than others:

Leucine: The most important of the BCAAs by far, leucine is the trigger for muscle protein synthesis as its presence activates a major metabolic pathway for hypertrophy, according to a study published in the Journal of Nutrition². Protein supplements like whey protein powder are particularly high in leucine and their effectiveness is what makes them so popular for bodybuilders.
Isoleucine: Works to shuttle glucose from the blood to the muscles more efficiently, which can help exercise performance by reducing time to fatigue³.
Valine: Valine works to regulate blood glucose and prevent muscle protein breakdown. Thus, it can help indirectly with muscle growth by promoting net positive muscle mass gain³.

6 Benefits of BCAAs

To be frank, the science on the effects of BCAA supplements is inconsistent, meaning they aren’t going to give most people life-changing results in terms of weight loss, muscle growth, or athletic performance. That said, let’s look at what research says about the potential BCAA benefits.

May Prevent Muscle Protein Breakdown

Putting on muscle mass isn’t just about building new muscle tissue. Muscle growth also relies on reducing muscle loss, especially considering that the rate of muscle damage and catabolism increases after resistance training.

Studies show⁴ that when blood concentrations of insulin and amino acids are high, it slows the rate of muscle protein breakdown. Indeed, dietitians in clinical settings will often use BCAA supplements to help treat muscle loss from conditions like cancer or sarcopenia⁵, a condition defined as the age-related decline of muscle mass and strength.

It’s important to note that in these studies, branched-chain amino acids simply prevented muscle loss, but did not necessarily help to build new muscle.

Potential Treatment for Liver Disease

Those with liver diseases like hepatitis or cirrhosis can experience hepatic encephalopathy due to the liver’s inability to clear out toxins that affect the brain. Impairments in motor function, confusion, memory issues, and even coma can occur as a result.

Studies have shown that BCAA supplements can be a better treatment for hepatic encephalopathy than some other dietary supplements, but only in combination with prescription medications, and they don’t prevent the condition from getting worse⁶.

In those with liver disease without hepatic encephalopathy, BCAA supplements may help reduce fatigue or muscle weakness⁷. All of this said, if you do have a liver disease, talk to a dietitian and your physician before you take BCAAs on your own.

Can Help With Muscle Growth

Probably the number one reason people take BCAAs is to build muscle. The science does show⁸ that branched-chain amino acids help to release the enzymes that cause muscle protein synthesis. As mentioned before, this is especially true of leucine.

The big asterisk here, however, is that no studies have been able to show that BCAA supplements cause an effect on muscle growth that is superior to the BCAAs you get from food or from whey protein powder (which is notoriously high in leucine⁹).

As a matter of fact, it has been found that consuming sports nutrition supplements containing intact protein, such as protein powder, may be more effective at building muscle mass than taking BCAAs individually¹⁰.

These findings make sense, considering whole food protein sources like whey, dairy products, and lean animal protein contain all of the essential amino acids, and sports nutrition research has shown that consuming all nine essential amino acids stimulates more muscle protein synthesis than consuming BCAAs alone¹¹.

May Support Muscle Recovery

One study¹² that had subjects cycle for two continuous hours found that branched-chain amino acid supplementation can support muscle recovery by mitigating the enzymes that lead to muscle damage.

Some studies¹³ have investigated BCAAs’ potential impact on delayed-onset muscle soreness (DOMS), with subjects reporting better muscle recovery following branched-chain amino acid supplementation compared to a placebo.

Interestingly, women experienced better results in terms of muscle soreness compared to men, with female subjects reporting 33% less¹⁴ muscle soreness when they took BCAAs along with a carbohydrate source.

May Reduce Fatigue

Some studies have shown that BCAAs taken during physical activity can reduce exercise fatigue by up to 15%¹⁵ compared to a placebo. Sounds promising, but the effects of BCAA concentrations on exercise fatigue are inconsistent, with just as many studies showing the compounds don’t have any effect at all¹⁶.

Can Improve Blood Sugar Control

As mentioned, one of the mechanisms of isoleucine is to influence insulin release. Since insulin normally releases after eating a meal, elevated blood levels of insulin signal the body that it has been fed. Being in a “fed state” tells the body it doesn’t need to break down muscle tissue for energy.

This function also serves those with insulin resistance, which is a major risk factor for the development of Type 2 diabetes. The effects of BCAAs like leucine and isoleucine cause the muscles to absorb more glucose, which results in lower blood levels of glucose, according to some studies¹⁷.

That said, there’s more bad news. These effects are not reliable, as many supporting findings come from studies done on mice and other clinical trials using human subjects found that BCAAs did not affect blood glucose levels¹⁸.

Potential Side Effects of BCAAs

Like creatine, branched-chain amino acids are a natural chemical compound. This means the body is used to metabolizing them from food, so they are unlikely to cause side effects in healthy individuals when supplemented as directed.

That said, BCAAs have the potential to worsen certain conditions like Type 2 diabetes, liver disease, heart disease, and maple syrup urine disease. Also, talk to a registered dietitian or your healthcare provider if you are considering taking BCAAs while taking prescription medication.

Who Should Take BCAAs?

So, based on the science we’ve discussed, it’s safe to say that the effects of branched-chain amino acid supplements aren’t nearly as impactful on their own as many are led to believe. Furthermore, as long as you are eating a balanced diet, especially one that is rich in protein from animal sources such as dairy products and lean meat, you are likely getting all of the amino acids you need without supplements.

That said, there are certain populations or situations where branched-chain amino acid supplementation can be beneficial.

Vegans and Vegetarians

Studies show that vegan athletes’ protein intake is much lower than vegetarian or omnivorous athletes¹⁹. Furthermore, the protein that is consumed from plant-based diets is typically lower in amino acids²⁰. Leucine can be obtained from legumes like lentils, but most other plant-based protein sources are low²¹ in lysine, isoleucine, and other essential amino acids like tryptophan.

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Vegans who are trying to build muscle are also presented with the challenge of many protein supplements containing dairy products or other animal-based ingredients. Thus, getting their BCAAs from BCAA supplements can be more appropriate.

Those With Liver Disease

There are some promising scientific findings in terms of using BCAA supplements in the treatments for liver disease when used under medical supervision. However, the benefits of BCAAs on liver disease are limited and inconsistent, so this direction of treatment should be thoroughly discussed with a healthcare provider to see if it is appropriate.

What Are BCAAs? Final Thoughts

Amino acids are the building blocks of muscle. So, consuming a high-protein diet for wellness and muscle gain is effective because of the actions of essential amino acids, which include branched-chain amino acids. Indeed, studies have shown that high protein intake is not only helpful for muscle gain, but is critical for weight loss as well²².

That said, most people who engage in regular resistance training consume a balanced diet that is rich in enough amino acids that render branched-chain amino acid supplementation unnecessary. The biggest exception to this is vegans who may not receive enough BCAAs through their diet and may benefit from supplements.

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At the end of the day, the best thing you can do for your wellness, weight loss, and athletic performance goals is to consume a balanced diet that is rich in lean proteins from both animal (such as seafood and poultry) and complete plant sources (like lentils and soybeans).

If you choose to take BCAA supplements, there aren’t many downsides or risks to doing so, but be aware that the benefits will likely be negligible.

What Are BCAAs? FAQs

Should I take BCAA every day?

BCAA supplements are generally safe to take as directed daily. However, daily intake is not recommended if you are consuming a nutritious, high-protein diet.

What does BCAA do to your body?

BCAAs have several purported benefits to the human body including changes in body composition, better muscle recovery, reduction of tryptophan and serotonin for better sleep, prevention of insulin resistance, and a potential treatment for certain states of liver disease.

What are the pros and cons of BCAAs?

The main pro of BCAAs is they can help supplement a low-protein diet. However, the con is that consuming a balanced diet makes the supplementation of BCAAs unnecessary.

Which is better BCAA or creatine?

Creatine has more science behind its effectiveness for athletic performance and muscle growth. Furthermore, creatine is much harder to obtain from diet than BCAAs, which makes it more practical to supplement.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any diseases.

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Destini Moody, RD, CSSD, LD

Destini Moody, RD, CSSD, LD is a sports dietitian and the head of performance nutrition for the NBA G League Ignite. In addition to working with pro athletes, Destini has ghostwritten four weight loss and wellness cookbooks. She also authors online content covering fitness and nutrition topics.

What Are BCAAs? A Registered Dietitian Explains