BCAA supplements can enhance your fitness routine, but should you take them?

Here’s what the science says about what branched-chain amino acids actually do.
woman lifting weights

BCAA powders taste delicious—but will they make me stronger? John Arano via Unsplash

Even with gyms reopening at limited capacity, it’s still safer to exercise at home or outdoors. So, we’re dubbing this September Muscle Month to help you keep up your fitness, power, and health in socially distant times.

People starting on a health journey often turn to supplements, probably because we like buying things more than we like doing hard physical work. One of the most ubiquitous powders aspiring athletes turn to are BCAAs, or branched-chain amino acids. These grown-up Kool-Aid mixes promise a boost for your muscles as well as a sweet and guilt-free beverage for you to enjoy after a workout.

But is this addition to your health regime necessary? Here’s a breakdown.

What are BCAAs?

There are three types of branched-chain amino acids our bodies use to create protein: leucine, isoleucine, and valine. As a reminder, amino acids are, to use parlance of your high school bio teacher, the “building blocks” of proteins, which your body uses not only for your biceps and quads but also your skin, hair, blood, bones, and a whole lot more. BCAAs make up three out of the nine essential amino acids. You have to consume all nine EAAs; your body cannot produce them on its own.

As supplements, BCAAs can be consumed in the form of Crystal Light-esque powders gym goers mix into water during and after a workout. But BCAAs are much more often consumed in the form of protein-rich foods like meat, dairy products, eggs, soy proteins, beans, nuts, and grains.

The three BCAAs have received special attention from athletic performance enthusiasts for decades, largely because of a handful of studies done in the early ’80s, which seemed to indicate that branched-chain amino acids were particularly beneficial for muscle protein synthesis. This appears to be especially true of leucine, which research indicates has a unique role in your body’s ability to repair and build muscles.

What are the benefits of BCAA supplementation?

When you train for strength, you’re injuring the muscles, making tiny tears that your body needs to weld together with more material. That repairing process gives your muscles more mass, which over time makes you stronger. Like everything our bodies do, muscle protein synthesis is chemically complicated, and can be affected by a variety of compounds, including hormones like testosterone and certain amino acids.

In theory, BCAAs help that repair process happen more efficiently by quickly mobilizing your body’s muscle-construction team. According to a 2017 paper on BCAAs and muscle protein synthesis, leucine triggers the necessary chemical reactions needed to fuse together muscle fibers, perhaps making this process more efficient. So when paired with resistance training, BCAAs may help your body better respond to the stress placed on them through exercise.

Unfortunately, there are not a ton of studies to support the idea that BCAA supplementation improves athletic performance in the short term, meaning that drinking BCAAs before your workout likely won’t make you squat more weight or swim faster. But there are quite a few papers that seem to suggest BCAA supplementation, when compared to a placebo, does help the body after your workout thanks to an improved muscle creation response—at least for healthy people doing vigorous strength training. This could reduce muscle soreness and get you back in the gym faster—and more training over time may improve your athletic performance.

What about EAAs?

BCAAs are a subset of EAAs, and while there’s decent proof that BCAA supplementation seems to mobilize muscle construction, it’s unclear how much of that benefit comes from leucine alone versus leucine in combination with the other two BCAAs or leucine in combination with the other eight EAAs. Leucine alone stimulates muscle creation. So does BCAA supplementation. So does EAA supplementation.

The key seems to be that the supplement needs to be leucine-rich. EAA powder may therefore be effective because it delivers your body a leucine boost, not because it has all the essential types of amino acids in it.

OK, but should I take BCAA supplements?

There are a few circumstances that may make BCAA supplementation beneficial. For one, if you’re a competitive athlete or bodybuilder that regularly puts a lot of stress on your muscles, BCAAs may help your body recover faster so you can train more often. A proper protein- and carb-rich meal may be just as (if not more) effective, though there is a practical benefit to being able to chug something pleasant, far-from-filling, and low-calorie directly after a punishing workout. It’s easy to prepare and consume in a few minutes and you can eat more of what you want for your actual meal.

The other circumstance in which BCAAs may be helpful is if you don’t eat a lot of leucine-rich foods and want to build muscle quickly. Animal products are naturally great sources of leucine, so if you’re eating meat and dairy regularly, supplementation probably isn’t necessary unless you’re going extremely hard in the gym.

Vegans who want to build significant muscle, however, may benefit from a leucine supplement, because plant-based proteins are generally lower in this amino acid than their animal-based counterparts. Here’s a graph illustrating this idea, from Anastasia Zinchenko, a vegan powerlifter with a PhD in biochemistry.

There’s also a reason you may not want to supplement with BCAAs if you already consume a high-animal-protein diet or aren’t committed to strength training. A leucine-rich diet may increase your risk of obesity or type 2 diabetes, in theory because the compound sends your body a “time to grow!” response, which isn’t limited to your glutes. That mechanism may explain part of why animal-based foods like red meat are associated with higher risk of obesity and diabetes, though it’s not yet clear how much it matters. As with everything in nutrition, it also depends on other lifestyle factors and your goals. If you’re exercising aggressively and regularly, a bit of added leucine may help more than it harms.

All that being said, if you’re looking for a physique or performance breakthrough, you’re not going to get it in the form of a (legal) pill, powder, or injection. It’s still largely determined by regular resistance training, adequate protein and fiber consumption, calories, hormones, and genetics. Muscle-building, like most things in life, simply doesn’t have a quick and easy solution.