What are BCAAs good for?

The branched-chain amino acids (BCAAs) are composed of three amino acids that the body cannot make itself and needs to acquire from the food that we eat. These three essential amino acids are Leucine, Isoleucine, and Valine.

These three branched-chain amino acids are particularly important to those of us who are interested in building bigger and stronger muscles in the gym.

In order to understand why this is, we have to first understand that our bodies are continually shifting between muscle protein breakdown and muscle protein synthesis. Muscle protein breakdown (MPB) is the process of breaking down damaged or unused muscle tissue in order to recycle the amino acids for other purposes in the body. Muscle protein synthesis (MPS) is the process of assembling the necessary amino acids in order to build new muscle tissue.

Although it is not possible (or even desirable) to completely stop the muscle protein breakdown process entirely, we would prefer to have more muscle protein synthesis than muscle protein breakdown happening throughout our body over a period of time.

What’s so special about these amino acids?

The truth is there’s nothing magical about this particular combination of amino acids. Sometimes I think we get caught up in the marketing hype of a particular supplement without really understanding what it is and why it may (or may not) help us to achieve our goals.

BCAA worth it?

Keep in mind that all 20 amino acids are needed to build any type of muscle tissue. Now having said that, muscle protein synthesis is stimulated primarily by the nine essential amino acids (EAA) And of these 9 EAAs, the 3 BCAAs (leucine, isoleucine, valine) appear to be the most important for muscle building. And of the three BCAAs, leucine is believed to be the most important of them all.

Interestingly, some research has shown that we might actually be better off taking leucine by itself rather than combined with isoleucine and valine in a BCAA supplement because all three BCAAs use the same mechanism to be absorbed and transported by the body. In other words, by taking all three at once, we are slowing down the absorption of leucine into the muscles because it is competing with isoleucine and valine.

Research has also shown that taking BCAAs by itself stimulates muscle protein synthesis (muscle building) less than the same amount of BCAAs you would get included in a whey protein shake that contains all of the essential amino acids.

Finally, even though the three BCAAs are the amino acids most responsible for building muscle in the body, you have to remember that all muscle protein synthesis will stop as soon as the supply of any of the nine essential amino acids (EAA) runs out.

So if this is the case, why would anyone consider taking a BCAA supplement by itself?

The potential benefits of a BCAA supplement

Fasted training

After an overnight fast, approximately 85% of the protein your body needs comes from your skeletal muscle. In other words, your body is in muscle breakdown mode in order to release the protein that your body needs to keep you alive.

BCAA worth it?

That’s the trade-off with fasted training.

Although your body is burning more fat for fuel because its carbohydrate stores are nearly empty, at the same time, it is also breaking down your body’s protein stores (i.e., muscles) in order to get the essential amino acids it needs to keep things running.

Many people don’t realize that exercise not only promotes muscle protein synthesis (muscle building), but it increases muscle protein breakdown as well.

By consuming all nine essential amino acids (not just the three BCAAs) before and after a workout, we are able to slow down the muscle protein breakdown process while still increasing the body’s muscular protein synthesis.

This is why people who train in a fasted state would often be better off if they consumed some type of complete protein before and after their workout.

Early morning training

I’ve had some people tell me that they often do their workout first thing in the morning and they simply don’t have time to eat and then wait for that meal to digest before starting their workout.

I usually suggest that they try a simple whey protein shake (not a loaded fruit smoothie) as soon as they get up, and by the time they get to the gym, it should have enough time to clear the stomach and suppress muscle protein breakdown.

If something like that still feels like too much sitting in your stomach during your workout, you might consider simply adding a scoop of BCAA powder in your morning juice or workout drink.

Even though the BCAAs alone won’t stop the muscle protein breakdown completely, it can at least slow it down a bit without filling up your stomach. Just be sure to consume some type of complete protein (such as breakfast or a whey protein shake) after your workout so that your body will be able to begin the muscle-building process.

Is BCAA worth it?

BCAAs during your workout

Despite the growing popularity of this practice in the gym, adding BCAA powder to your workout drink doesn’t really seem to be necessary unless you are either training in a fasted state or your workouts typically last for more than 60-90 minutes.

Sometimes I think we fall into this trap of overly complicating things.

Next time you are at your gym look around and notice all of the people who are standing around checking their phone with one hand while mindlessly shaking their fancy workout cocktail in the other hand. These are often the same people who tend to look the same month after month.

Unless we are running a long-distance race or sweating profusely in our air-conditioned gym, we probably don’t need an electrolyte balanced workout drink. And unless we haven’t eaten anything in the last several hours, we probably don’t need to add BCAA powder to our workout drink either.

Instead of worrying about all of this little stuff, most of us should simply fill up a water bottle (with water) and focus on lifting more of the big stuff.

Post-workout BCAAs

Most people get their BCAAs from their post-workout protein shake. If you use a whey based shake, you probably don’t need to supplement with additional BCAAs. However, if you use a different type of post-workout protein such as casein or from a vegetarian protein source (soy, rice, pea) there is some evidence that you might benefit from adding a scoop of BCAA powder because of the lower leucine content.

BCAAs and reduced calorie diets

If we are attempting to lose weight and are on a low-calorie diet, we need to make sure that we are still getting enough protein in our diet to reduce the muscle protein breakdown process as much as possible.

We all need a certain amount of protein in our diet just to keep things running, however, if we are interested in muscle growth, we will need to increase our protein consumption even more so that we have all of the amino acids available we’ll require to build new muscle tissue.

The bottom line…

The branched-chain amino acids (BCAA) are composed of three essential amino acids (leucine, isoleucine, valine) that the body cannot make itself and needs to get from the food that we eat. However, there is nothing magical about this particular combination because we still require all twenty amino acids to build new muscle.

Muscle protein synthesis is stimulated primarily by the nine essential amino acids (EAA). And of these 9 EAAs, the 3 BCAAs (leucine, isoleucine, valine) appear to be the most important for muscle building. Having said that, getting enough amino acids (i.e., protein) is only part of the equation. You still have to go to the gym and lift a lot of heavy objects if you want to see any results.

Even though most of us would be better off simply getting our BCAAs from a whey protein shake or eating actual food that contains all of the essential amino acids, you might consider a BCAA supplement if you typically train fasted or first thing in the morning in order to suppress muscle protein breakdown during your workout.

Finally, a BCAA supplement may be appropriate if you are on a reduced calorie diet and are not consuming enough protein to keep your body from breaking down muscle tissue. Keep in mind, however, that BCAAs can only slow down the muscle protein breakdown process. In order to stop it (at least temporarily), you will need to consume a complete protein that contains all nine essential amino acids like meat, fish, eggs, milk, cheese, quinoa, yogurt, or whey.


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Katsanos CS, et al., Whey protein ingestion in elderly persons results in greater muscle protein accrual than ingestion of its constituent essential amino acid content. Nutr Res. 2008 Oct;28(10):651-8.

Negro M, et al., Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system. J Sports Med Phys Fitness. 2008 Sep;48(3):347-51.

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Drew Kimble CSCS*D, CPT
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