Should You Be Taking BCAAs?

Branched Chain Amino Acids (BCAAs) are among the most popular supplements for athletes. But are they really necessary?


BCAAs, or branched chain amino acids, are one of the most popular supplements in performance training. The term refers to three amino acids: leucine, isoleucine and valine. These three are all essential amino acids, meaning they cannot be made by the human body. Supplementing with them can be helpful in people who do not get sufficient protein in their diets for building and maintaining muscle. Most BCAA supplements contain a 2:1:1 ratio of leucine, isoleucine and valine.


The reason leucine, isoleucine and valine are called branched is because of their chemical structure. Each of them contains a "side chain" of one carbon atom and three hydrogen atoms. To understand the role of branched chain amino acids in your body, it helps to understand amino acids.

According to the National Library of Medicine, amino acids are "organic compounds that combine to form proteins." More specifically, they're organic compounds that contain at least one amino group and one carboxyl group. Amino acids are mainly known for their role as the building blocks of protein. Although over 50 amino acids are currently known to exist, only about 20 of them are used to make the proteins in the body. How amino acids come together to form a protein helps determine the structure and function of that protein.

There are three groups of amino acids: essential, nonessential and conditional. Essential amino acids are the nine amino acids that cannot be made by the human body. We must get essential amino acids through food. Nonessential amino acids are amino acids that our bodies can produce. Conditional amino acids are amino acids that a healthy human body can produce, but certain conditions might limit one's ability to do so, forcing one to turn to diet and/or supplementation to get them.

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What are the Benefits of BCAAs?


One reason BCAAs are different from other amino acids is that they aren't degraded by the liver. Every other amino acid is processed by the gut and the liver before being circulated throughout the body. BCAAs head directly into the bloodstream.

In a general sense, branched chain amino acids do a few key things inside our body. Leucine promotes muscle protein synthesis, meaning it can help you build muscle mass quicker and more efficiently. Isoleucine increases glucose uptake in the muscle and helps turn it into energy. According to, a website that collates scientific research and disseminates info on nutrition and supplements, "isoleucine can be seen as the BCAA which mediates glucose uptake (into a cell) and breakdown (into energy) to a larger degree than other amino acids." Valine also can be converted to glucose within the body.

Obviously, leucine and isoleucine are important for athletes since they're closely tied to muscle growth and energy production. Studies have connected BCAAs with reduced fatigue, increased post-exercise muscle growth and reduced levels of post-exercise muscle damage. However, many of these studies center around participants who either aren't eating enough protein or are fairly new to training. For example, this 1997 study found that branched chain amino acids supplementation helped competitive wrestlers maintain more muscle over a three-week period. However, the participants were all in a calorie deficit and weren't consuming enough protein. It's no surprise, then, that the BCAAs had such a result under these conditions.

As for reports of reduced fatigue, there may be a very mild effect in highly trained individuals. It's likely that the anti-fatigue effects of branched chain amino acids only really apply to untrained or lightly trained people. "In regards to the anti-fatigue effects, it is highly plausible that this will only apply to untrained or lightly trained persons doing prolonged exercise. There does appear to be a difference between trained and untrained persons, and perhaps this is due to less tolerance to exercise-induced sedation (fatigue tends to set in earlier in newbies, so an anti-fatigue effect is going to affect them more)," writes Kurtis Frank, lead researcher at Examine.

What are the Side Effects of BCAAs?

The use of BCAAs is regarded as safe for nearly every population, except for people afflicted with ALS, or Lou Gehrig's Disease.  There are no scientifically documented adverse side effects.

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Where are BCAAs Found?


Even if you don't take a dedicated BCAA supplement, you're already consuming them.

BCAAs are an essential part of the human diet, and since you cannot produce them yourself, you must get them from food. Branched chain amino acids are actually present in all protein-containing foods. Red meat and dairy foods are particularly high in branched chain amino acids, but so are things like chicken, fish, eggs, beans, lentils, nuts and soy protein. Even if you're a vegetarian or a vegan, you are probably getting them from beans and rice or a grilled cheese sandwich. If you have a balanced diet and are consuming enough protein, you're likely consuming enough BCAAs.

Should I Take a BCAA Supplement?


It largely depends on your diet.

Examine states that "BCAA supplementation, for people with low dietary protein intake, can promote muscle protein synthesis and increase muscle growth over time."

The words "low dietary protein intake" are crucial. If you're already getting sufficient protein in your diet, branched chain amino acids supplements are probably not worth your money. You're better off sticking to real foods and using supplements that contain protein—such as whey protein products—rather than relying on BCAAs.

However, if you're intentionally not getting enough amino acids in your diet, branched chain amino acids supplements could certainly be useful. They would allow you to consume valuable amino acids without consuming unwanted calories. If your diet doesn't include enough essential amino acids, your body starts breaking down muscle tissue as a way to access them. This is obviously a terrible thing for athletes—the body essentially cannibalizes its own muscle mass for fuel. This alone is a major issue, but a lack of essential amino acids can also result in reduced energy and attentiveness.

Why might one intentionally not consume enough amino acids via diet? Perhaps they're trying to maintain a calorie deficit, or maybe they're committed to what's known as "fasted training."

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Fasted training refers to training in a state where your insulin levels are close to their baseline. When we eat food, it raises our insulin levels. Insulin levels can remain elevated for 3-6 hours (if not longer) after we eat, depending on how much we ate.

When your insulin levels are up, your body isn't in an optimal state to burn fat. The idea behind fasted training is that fat loss is accelerated when training with baseline insulin levels. However, muscle breakdown is also increased when you're training in a fasted state. A branched chain amino acids supplement can help avoid that muscle breakdown without raising your insulin levels the way a meal would, allowing you to reap the full benefits of fasted training.

The Verdict


While advertising or your local meathead might make it seem like a BCAA supplement is indispensable, that isn't necessarily true. Essential amino acids are critical for athletes, no doubt. But if you're eating the right way and consuming between 1.0-1.5 grams of protein per kilogram of bodyweight per day, you should be all set.

"If you're eating an overall healthy diet and you're balancing your protein throughout the day, you really don't need to take BCAAs in supplement form," says Joy Dubost, RD and a spokesperson for the American Dietetic Association.

If you'd like to give them a try, feel free—BCAAs aren't banned by the NCAA or high school athletic associations. There also seem to be little to no side effects associated with BCAA supplements. Most branched chain amino acids supplements recommend taking them before, during or after training (or a combination of the three). If you're searching for a BCAA supplement that's guaranteed for quality, look for NSF certification.

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