Walk into most gyms these days and it won’t be long before you spot someone sipping from a colourful shaker full of a sweet-smelling drink. Ask them what’s inside and you’ll probably hear the same answer, “BCAAs”. Short for branched-chain amino acids, these supplements have taken on a bit of a cult status in the fitness world. They’re in everything from pre-workouts to protein powders and even standalone drinks promising everything from faster recovery to better gains.
But is there more to this trend than just flashy marketing and influencer posts? Is the science actually behind the hype? Or are BCAAs just another supplement that sounds good on paper but delivers very little in real life?
Let’s unpack it.
What’s the Theory Behind BCAAs?
BCAAs refer to three essential amino acids: leucine, isoleucine, and valine. The body can’t produce on its own. They must be obtained through food or supplements. Of the three, leucine tends to get most of the spotlight because it’s believed to play a key role in stimulating muscle protein synthesis. In theory, by flooding the body with leucine and the other BCAAs, you can kickstart muscle building and reduce the breakdown of muscle tissue. This is especially useful during workouts or when in a calorie deficit.
BCAA supplements are usually taken around training. That’s before, during, or after, with the goal of reducing muscle soreness, speeding up recovery, or even preventing muscle loss altogether.
Sounds great, right? But what does the actual research say?
What’s the Evidence?
Here’s where things start to get interesting. While it’s true that BCAAs are involved in muscle protein synthesis, the story isn’t quite as clear-cut as supplement companies would like us to believe.
Several studies have shown that BCAA supplementation on its own doesn’t significantly improve muscle growth or recovery in people who are already eating enough protein. This is because building muscle requires all nine essential amino acids, not just three, and most whole food protein sources already contain BCAAs in abundance. For someone drinking a whey shake or eating enough chicken, fish, dairy, or tofu, there may be no additional benefit from taking BCAAs separately.
A 2017 review published in the Journal of the International Society of Sports Nutrition pointed out that while BCAAs do stimulate muscle protein synthesis, they’re not enough on their own to promote a full anabolic response unless all essential amino acids are present. In other words, the body needs the full toolkit, not just a few fancy tools
There is some evidence that BCAAs might help reduce delayed onset muscle soreness (DOMS), but again, the effect is modest and not consistently found across studies.
What about inflammation?
Now, here’s where things get more nuanced and interesting. A recent systematic review published in the International Journal of Nutrition, Pharmacology, Neurological Diseases (2025) looked at whether BCAA supplementation, particularly those high in leucine, could reduce levels of interleukin-6 (IL-6), a key inflammatory marker associated with muscle catabolism and chronic illness.
The review included 13 studies and 770 participants, ranging from healthy athletes to older adults with sarcopenia. The researchers found that while the results were mixed, six studies reported significant reductions in IL-6 following BCAA or leucine-rich supplementation. Some studies didn’t show a benefit and others lacked statistical clarity, but there was a recurring theme: in people with elevated baseline inflammation, such as those recovering from surgery or managing age-related muscle loss, BCAA supplementation may have a genuine anti-inflammatory effect.
One standout study involved sarcopenic patients receiving BCAA alongside calcium, vitamin D, and exercise. Their IL-6 levels significantly dropped. Another study involving post-surgery patients found that BCAA plus insulin blunted the typical rise in inflammation compared to insulin alone. However, it’s worth noting that many of these interventions used combined approaches, so it’s hard to isolate the effects of BCAAs entirely.
In short, there may be a place for BCAAs in managing inflammation, especially in clinical or older populations. But more focused research is needed before firm recommendations can be made and ideally, that research should come from independent scientists, not supplement companies.
Why All the Hype Then?
The fitness industry loves a good supplement story, and BCAAs have the perfect ingredients for one. They’ve got a bit of science behind them, they sound technical enough to impress your gym mates, and they come in every flavour under the sun. Add a few before-and-after photos and some influencer endorsements, and you’ve got a marketing dream.
But it’s not just the ads. BCAA use is also wrapped up in gym culture. They’re seen as a badge of effort. Something you drink mid-session to show you’re serious about recovery. It’s part ritual, part habit and part “what everyone else is doing.”
There’s also the appeal of taking something when you don’t want a full meal or protein shake, say, when training fasted, or during a cut. And to be fair, in those scenarios, sipping on BCAAs might be slightly better than nothing. But they’re still not essential.
Are they worth it?
So, are BCAAs really worth adding to your supplement stack? Well, that depends entirely on your context. If you’re already eating enough high-quality protein throughout the day from meals or shakes, then the short answer is, probably not. You’re likely getting plenty of BCAAs naturally through those sources, especially leucine, which is abundant in animal-based proteins and present in plant-based ones too. In this case, adding a BCAA drink on top might be more about habit or taste than actual benefit.
However, if you’re training fasted, on a low-protein diet, or working with older clients who are at risk of muscle loss, then BCAAs might have some value, particularly for reducing muscle breakdown and supporting recovery. The evidence around inflammation, as we saw earlier, suggests they may have a role to play in certain clinical or high-risk populations. But again, they’re not magic. They’re not a replacement for protein, nor are they a shortcut to building muscle.
It’s also worth considering the cost. BCAA supplements aren’t cheap and for many people, the money could be better spent on food that provides all the essential amino acids, or even just a good-quality protein powder. If you enjoy sipping on something fruity during your session and it helps you stay hydrated or feel motivated, then fair enough. But for most active people with a balanced diet, BCAAs are more of a “nice to have” than a “need to have.”
Here’s a quick summary of how they stack up in different scenarios:
| Scenario | Are BCAAs useful? |
|---|---|
| Eating enough protein? | Probably not necessary |
| Training fasted or on low protein intake? | Might help a bit |
| Managing illness, sarcopenia, or muscle wasting? | Can be useful under medical guidance |
| Just like the taste or ritual? | Fine – but it’s a luxury, not a need |
So really, it’s not about whether BCAAs are good or bad. It’s about when and for whom they might make sense. That kind of nuance is exactly what we explore in the nutrition coach course and nutrition course we run at TRAINFITNESS, because making sound, evidence-based decisions around supplements is a key skill for anyone supporting others with nutrition and training.
So where does that leave us?
Supplements will always have a place in the fitness and nutrition world. But as with anything, they should be used intentionally, not just because the tub says you’ll build muscle faster or recover like a superhero.
If you’re working as a personal trainer or nutrition coach, it’s really important to stay curious and cautious. Ask questions. Dig into the research. And not just the studies funded by supplement companies. Look for independent reviews, systematic studies, and trials with good methodology, like the one we discussed above.
This is exactly the kind of critical thinking we encourage in our nutrition coach course. Whether you’re just starting out or looking to broaden your skillset, our nutrition course gives you the tools to assess supplement claims, understand the science, and give grounded advice to your clients.
Because in the end, being evidence-based isn’t just about quoting studies, it’s about thinking like a scientist, even if you’re wearing gym kit.
References
- Jackman SR, Witard OC, Jeukendrup AE, Tipton KD. (2017). Branched-chain amino acid ingestion stimulates muscle protein synthesis but doesn’t increase net muscle protein accrual. Journal of the International Society of Sports Nutrition. Click here to review the full research article.
- Wulandari Y, Sunardi D. (2025). Systematic review of branched-chain amino acid supplementation high in leucine on interleukin-6. International Journal of Nutrition, Pharmacology, Neurological Diseases. Click here to review the full research article.
- De Bandt JP, Cynober L. (2006). Therapeutic use of branched-chain amino acids in burn, trauma, and sepsis. Journal of Nutrition. Click here to review the full research article.
- Elango R et al. (2016). Safety and tolerability of leucine supplementation in elderly men. Journal of Nutrition. Click here to review the full research article.
- Kimball SR, Jefferson LS. (2006). Signaling pathways and molecular mechanisms through which branched-chain amino acids mediate translational control of protein synthesis. Journal of Nutrition. Click here to review the full research article.
Protein, Performance & Practical Coaching. Learn It All!
If you’re serious about helping clients make informed, evidence-based choices around food and supplements, the Level 4 Nutrition Coach course at TRAINFITNESS is the next step. You’ll learn the science of nutrition for health and performance, including how to tailor protein intake for different training goals. For example, did you know that the average exerciser needs around 1.2–2.0g of protein per kg of body weight per day, even more if they’re in a calorie deficit or training intensely? This course breaks down what those numbers actually mean in practice and how to coach clients through real-world nutrition strategies. Whether you’re supporting someone training for their first 10K or working with clients managing body composition or fatigue, this course gives you the practical know-how to do it confidently, backed by science, not fads. It’s all online, recognised by CIMSPA and built around the realities of being a busy fitness professional.
Nutrition Coach Course – Distance Study
