BCAAs: Benefits, Side Effects & Dosage


What are Branched Chain Amino Acids (BCAAs)?

Amino acids are compounds that contribute to the formation of protein in the body. They play a role in every metabolic process and affect energy, mood, brain function and even muscle function. Our bodies also need amino acids for growing healthy tissues in muscles, bones, skin and hair. Quite simply, without amino acids, we would not exist.

A quick description (or review, if you already know this) of essential vs. non-essential amino acids — essential amino acids are those that the body does not produce on its own. They can only be obtained by consuming food. Luckily, they are present in a wide variety of foods including meat, dairy, eggs, and many different kinds of vegetables.

Non-essential amino acids, on the other hand, can be synthesized in the body. They’re equally as important, but we don’t need to worry as much about consuming them because our body already takes care of it in most cases.

Branched-chain amino acids (BCAAs) are a group of three essential amino acids — leucine, isoleucine and valine. BCAAs are present in many foods, but some people also choose to take them as supplements. They’re wildly popular in sports nutrition because they work together to keep muscles strong and repair them when damage occurs. They can also improve athletic performance and assist with fat loss.

The Amino Acids

Studies show that BCAAs can help athletes and non-athletes build and retain muscle, shorten recovery time after exercise, reduce feelings of fatigue during activity and improve performance. Each of the three BCAAs — leucine, isoleucine and valine — play a unique but synergistic role (x).


Leucine is the most abundant BCAA and is most associated with the building and repair of muscle fibers as a result of its conversion to hydroxymethyl butyrate (HMB) (x, x). It directly stimulates muscle synthesis.


Isoleucine is involved in the regulation of blood sugar and energy levels. It also is essential for hemoglobin production (x). This action of isoleucine has an important function in both general and exercise nutrition. More on this later.


Valine is also considered important for muscle growth and repair and plays a role in the expression of certain neurotransmitters that affect feelings of exhaustion (x). In other words, valine is believed to contribute to the anti-fatigue effect of BCAAs.

Benefits of BCAAs

BCAAs for Muscle Growth

The claim that BCAA supplements help to build muscle mass is up for debate. Some speculate that the protein-synthesizing effects of BCAAs lead to a direct increase in quantifiable muscle mass. Unfortunately, there isn’t much evidence to back this up (x).

Even though the science to support BCAA’s role in building muscle is limited, BCAA supplementation is still widely used in sports nutrition. Many athletes swear by it. Why would this be?

While research cannot yet produce consistent evidence that BCAA supplementation alone directly builds muscle, there are studies that show that taking BCAA supplements with other complete proteins (such as whey protein) enhances the anabolic effect of the complete protein (x).

There’s another mechanism by which BCAAs may promote muscle growth. Blood glucose and insulin levels play a role in muscle metabolism. After a strenuous workout, BCAAs, especially isoleucine, promote the uptake of glucose into the muscle, which prevents muscle breakdown and encourages growth (x).

Muscle Recovery

Less controversial and more thoroughly exemplified in research is the ability of BCAAs to help muscles recover after exercise.

BCAA supplements could repair muscle fibers damaged by exercise or certain medical conditions. Leucine in particular triggers the production of protein in muscle. Together, they also help the body reuse other amino acids and stimulate the release of insulin — all of which allow the body to replace and repair lost and damaged muscle (x).

In one study, 16 males were split into two groups. One group consumed a typical amount of BCAAs and the remaining group took additional BCAA supplements. As a result, the group receiving the extra supplements had lower blood levels of the enzymes CK and LDH after prolonged exercise. The results of the study indicate that BCAA helps to maintain muscle tissue and minimize damage (x).

Furthermore, an analysis of eight studies concluded that “use of BCAAs is better than passive recovery or rest after various forms of exhaustive and damaging exercise.” They reduce muscle soreness and help preserve muscle function after a tough workout (x).

BCAAs for Improved Strength and Endurance

An interesting thing happens when you engage in strenuous exercise — the body produces tryptophan, which causes the release of serotonin in the brain. It’s possible that this release of serotonin contributes to feelings of fatigue after exercising for some time.

What does this have to do with BCAAs? Tryptophan is an amino acid that competes with valine in the body. As you exercise and valine levels diminish, tryptophan levels rise and have the opportunity to influence serotonin levels. It’s therefore possible that supplemental BCAAs can reduce the feeling of tiredness during exercise because the extra valine will keep tryptophan — and hence serotonin — at bay (x, x).

Less fatigue logically means more strength and better endurance. But BCAAs, particularly leucine, has a history of helping increase strength independent of muscle mass. In other words, it doesn’t only make your muscles bigger, it can actually make the individual fibers stronger. A 12-week study found that supplementing with four grams of leucine per day enhanced strength performance in men new to strength training (x).

Supports Insulin Release and Balances Blood Sugar

We know that isoleucine helps stabilize blood sugar. Aside from this being useful during exercise and recovery, stable blood sugar promotes health in many other ways.

Low blood sugar, or hypoglycemia, can cause hunger, irritability, shakiness and anxiety, for example. On the other hand, chronically elevated blood sugar, or hyperglycemia, is associated with metabolic syndrome and diabetes. It can also lead to adrenal fatigue, weight gain, inflammation and cardiovascular disease (x, x).

Reduces Body Fat

It’s important to maintain the muscle you have when you want to lose weight. Muscle preservation helps your body to continue burning fat. However, when you’re eating less, the body will use its muscle for the energy it needs. BCAA supplements give you energy and prevent muscles from breaking down. In combination with a sensible diet and regular exercise routine, BCAAs can help you reach your health and fitness goals. They support the fat-burning effect of exercise by delivering amino acids directly to muscles and minimizing protein breakdown. In short, consuming BCAA can result in more body fat reduction (x, x).

Liver Support

A number of studies show BCAA supplementation to be helpful in the treatment of liver diseases. They support protein synthesis, reduce protein loss, improve cognitive function and have positive effects on people with liver cirrhosis and hepatic encephalopathy (x).

BCAA Benefits

Side Effects and Dosage for BCAAs

BCAA supplements are available in the form of a powder or capsule. In its powdered form, it is more cost-effective, potent and can be made into a shake or smoothie. Capsules are a great option for those who don’t like the taste of powders or who don’t have the time to mix up a drink.

One should consume this supplement 30 minutes before any exercise or 30 minutes afterwards. Taking it with a meal is generally preferable, as it may help eliminate any feelings of nausea that may occur. The optimal dosage for this supplement is 1,500 mg, three times a day.

BCAA supplements are safe for most people and have no known drug interactions. However, pregnant women should rely on food sources of BCAAs rather than supplements. Side effects of supplementation can include feelings of fatigue, muscle weakness, muscle pain, loss of coordination and stomach discomfort.

The Bottom Line

Why take BCAAs? Supplementing with BCAAs can be beneficial to any athlete, bodybuilder, runner or cross-fitter. They could improve your performance, decrease recovery time, delay fatigue and support the development of muscle tissue. These amino acids can also help stabilize blood sugar and help you lose unwanted fat.

You can, and should, obtain amino acids from a variety of high-protein foods like meat, dairy products, eggs and legumes. However, athletes or those looking for an additional boost rely on BCAA supplements to give their bodies more of these essential building blocks. Make your workouts count — protect your gains!

By: Jessica Moon

About the author

Jessica Moon

Let's Be Friends