Article Summary
Are branched-chain amino acids (BCAAs) worth taking? Is there scientific evidence that they help to build or maintain muscle mass?
Suffice it to say that there is a lot of conflicting research on the topic of BCAA supplementation. After you cut through the marketing BS and BCAA manufacturer-funded garbage studies, there’s still a pretty muddied scientific stance on BCAA supplementation.
On the whole, however, BCAAs likely fall short of their marketing hype. You simply do not need BCAA supplements to build muscle because many vegan foods like tofu and pea protein are abundantly rich in BCAAs (and far less expensive!)
Although diet and training are by far the most important drivers of muscle growth and fat loss, BCAAs do have their place in a proper bodybuilding regime.
According to the latest research, BCAA supplements are beneficial in two specific circumstances:
Supplementation during a serious caloric deficit in which you are at a low body fat percentage and struggle to get enough protein (specifically the amino acid leucine).
Supplementation during fasted training as a muscle sparing strategy.
Please read the rest of the article to learn everything you need to know about BCAAs.
What are BCAAs?
There are nine essential amino acids – the building blocks of protein – that must be consumed in your diet because your body cannot produce them. Three of these essential amino acids – leucine, isoleucine, and valine – are called branched-chain amino acids (BCAAs) because of their branched molecular structures.
While most amino acids are broken down in your liver, BCAAs are primarily broken down in your muscle and therefore believed to improve exercise performance and reduce muscle breakdown, particularly during fasted training.
Leucine, in particular, is the MVP of muscle protein synthesis (MPS) because of its star role in building muscle and reducing muscle breakdown.
Should You Take BCAA Supplements?
If you are skeptical of the supplement industry, you have good reason to be.
Bodybuilding supplements are not regulated by the FDA and are often backed by loose pseudoscience. It is alarmingly easy to get a supplement on the market.
But if you look around at various fitness YouTube videos, BodyBuilding.com forums, and “broscience” blogs, you'll find plenty of bodybuilders who swear by their use of various supplements.
Don’t buy into the hype. Many of these same people sell supplements or have been brainwashed by jacked steroid users who shill supplements as their secret to getting ripped.
To be fair, BCAA supplements are one of the most useful, research-backed supplements on the market. There are many studies that tout the legitimate benefits of consuming BCAAs. But don’t be fooled by poor study designs and manufacturer-funded research.
For example, there is plenty of research demonstrating the benefits of BCAA supplementation for subjects following a caloric deficit or consuming low-protein diets.
The most widely cited pro-BCAA supplement study was conducted in 1997 with thirty-one competitive male wrestlers who followed a moderate caloric deficit for 19 days.
The researchers found that BCAA supplementation, in combination with the subjects’ low-protein, energy-restricted diets, induced significant and preferential losses of visceral adipose tissue (i.e. fat) and allowed maintenance of high levels of physical performance.
All this really tells us is that we should use a BCAA supplement if we are consuming less protein than our bodies need during a period of caloric restriction to avoid muscle catabolism.
A meta-analysis of BCAA supplementation literature arrived at the same finding: BCAA supplementation in combination with a moderate caloric deficit has been shown to optimize fat losses without losing muscle or strength.
Again, this isn’t very helpful information. If you aren’t consuming enough protein during a caloric deficit, ingesting amino acids in the form of a BCAA supplement will obviously help you maintain lean body mass.
What we really need is a study that analyzes the effects of BCAA supplementation for resistance-trained athletes consuming high-protein diets!
Thankfully…there are two such studies!
In one of the most comprehensive studies on BCAA supplementation, researchers at Baylor University analyzed the effects of eight weeks of heavy resistance training combined with BCAA supplementation on body composition and muscle performance of 19 non-resistance-trained males.
The researchers concluded that BCAA supplementation failed to alter body composition, muscle strength, or muscle endurance.
Another study from Leeds University analyzed the effects of L-leucine supplementation alone (not all three branched chain amino acids) on strength, lean tissue mass, and fat mass of 26 untrained men following a non-energy-restricted diet during a 12-week resistance training program.
As a brief aside, L-leucine is simply the left rotated form of the amino acid leucine. The body more easily absorbs left rotated amino acids, which are also commonly called “free form” amino acids.
Just like the Baylor University study, researchers found no effect of L-leucine supplementation (4 grams per day) on body composition over the twelve weeks of resistance exercise training.
But in partial contradiction to the Baylor University study, the Leeds University researchers did find improvement in the L-leucine group subjects’ 5 repetition maximum (5RM) strength for five out of the eight exercises tested. The percentage total 5RM strength gains were 40.8% and 31.0% for the L-leucine and placebo groups, respectively.
If you’ve seen BCAA ads stating that a 4-gram daily dose of L-leucine has been shown in a clinical study to increase 5RM strength by over 40% in just 12 weeks, then this is the study they are using.
While this is technically a correct statement, you should take it with a grain of salt. The subjects were novice weightlifters with zero prior training experience. Furthermore, the placebo group experienced a similar, albeit lower, explosion in strength gains over the same 12-week period (31.0% vs. 40.8%).
The study concludes that 4 grams per day of leucine supplementation may be used as a nutritional supplement to enhance strength performance, but these findings aren’t necessarily applicable to experienced strength athletes.
So although there’s a pretty muddied stance on BCAA supplementation in the scientific literature, we can reach a few conclusions from the peer-reviewed studies above:
BCAA supplementation is an effective muscle sparring strategy if you are following an energy-restricted diet (i.e. a caloric deficit). BCAA supplementation might also enhance strength performance.
If you are consuming enough BCAAs from dietary protein (including protein powder), then supplementing with BCAAs is unlikely to provide additional benefit.
Leucine supplementation alone appears to be nearly as effective in stimulating muscle protein synthesis as when all branched chain amino acids are consumed.
When You Should Consider Taking a BCAA Supplement
You’ve likely heard that if you do too much cardio, don’t ingest enough protein, or if you over train, then you risk cannibalizing your muscle.
While there is truth to these concerns, the science isn’t quite so simple. Your body breaks down and utilizes free BCAAs in your muscle first before your body cannibalizes muscle tissue. Your body takes these BCAAs and converts them to glucose through a process called gluconeogenesis (GNG) and uses the glucose for energy.
This process ensures BCAAs do have a muscle sparing action, but this is only helpful in certain situations, namely, if you are in a moderate caloric deficit or engaging in fasted training.
Specifically, the benefit of free form BCAA supplements lies in their ability to quickly flood the blood stream and muscles with high amounts of BCAA, especially leucine, to prevent muscle catabolism.
While your body absorbs amino acids from vegan protein powders (like pea protein) rather quickly (it takes around 45 minutes after consumption before your body begins to extract and absorb amino acids from protein powder), the ingestion of 5 grams of BCAAs from protein powder does not create the same metabolic response as the ingestion of 5 grams of free-form BCAAs from BCAA supplements.
Taking a BCAA supplement before intense cardio, particularly fasted cardio or cardio while following a caloric deficit, will help to preserve muscle mass.
For example, a study from the College of Charleston showed that BCAA supplementation in trained individuals performing resistance training while on a hypocaloric diet maintained lean mass and preserved skeletal muscle performance while losing fat mass.
Although informative, it is worth noting that the subjects didn’t receive a normal dose of BCAAs. The BCAA group received a whopping 28 grams of BCAAs daily (14 grams pre-workout and 14 grams post-workout) while the placebo group received 28 grams of a carbohydrate/electrolyte supplements (14 grams pre-workout and 14 grams post-workout).
Personally, I rarely train fasted and only use BCAAs when I drop below 10% body fat during a cut. While I maintain nearly all of my strength and muscle mass during deep cuts, I cannot attribute my lean body mass (LBM) retention to BCAA supplementation. I carefully plan my diet and training to achieve these results.
Even if you are following a caloric deficit, you can get all of your BCAAs from high-protein vegan foods to prevent muscle catabolism.
For me, supplementing with BCAAs is just to be safe so I don’t risk burning any of my hard-earned vegan gains during a caloric deficit. If an experienced weightlifter (4+ years of weightlifting experience) loses just one pound of muscle while cutting, it will likely take 2 to 6 months of intense weightlifting to gain that pound of muscle back during his/her next bulking period! I'd rather play it safe and supplement with BCAAs to ensure I am doing everything in my power to maintain LBM.
I have also experimented with leucine supplementation for the purpose of LBM retention during cuts, but cannot directly attribute any positive benefits to it either.
Doesn’t BCAA supplementation assist in reducing exercise-induced muscle soreness?
Nope, current research doesn’t support this common belief. A study funded by MusclePharm Corp (a manufacturer of BCAA supplements), which was surprisingly unbiased, found that BCAA supplementation does not reduce muscle soreness, nor does it appear to aid in attenuating the reduction of muscular performance following intense resistance training.
What You Should Take Instead of BCAAs
There is plenty of research that proves raising BCAA levels (leucine in particular) before and after exercise helps us build more muscle and maintain lean mass. However, there is little evidence that consuming BCAAs through supplementation is more effective than a high protein diet.
I think this excerpt from a review of BCAA research literature sums it up well:
“No data support the finding that oral supplementation with amino acids, in contrast to dietary protein, as the source of amino acids is more effective.”
If you are in a caloric surplus and eat enough protein, particularly leucine, you do not need a BCAA supplement. See my general targets for protein consumption in the table below.
The truth of the matter is that there are plenty of high-protein vegan foods and less expensive vegan protein supplements that are loaded with BCAAs.
For example, pea protein powders can be as high as 20% BCAAs by weight, surpassing even most whey protein powders!
On top of that, every 30 gram serving of pea protein gives you the required amount of leucine that is optimal for muscle growth, which is about 2.5 grams for the average male bodybuilder.
This is what makes pea protein such a great protein source! It is packed with essential amino acids, especially BCAAs!
What Are The Best Food Sources of BCAAs?
BCAAs are found in a number of protein-rich foods, including quinoa, pumpkin seeds, alfalfa seeds, kidney beans, tofu, sesame flour, and sunflower seed flour. One of the best sources, however, is pea protein concentrate, which has one of the highest concentrations of leucine compared to other vegan protein sources.
As previously mentioned, leucine is a particularly important amino acid because it acts as a trigger for muscle protein synthesis (MPS). Most plant proteins have a relatively low leucine content, which reduces their anabolic properties. Therefore, it is very important to consume a variety of high-leucine foods.
A 100-gram serving of pea protein concentrate has about 9.2 grams of leucine compared to 0.8 grams of leucine in 100 grams of dry quinoa, 0.7 grams of leucine in 100 grams of tofu, 1.6 grams of leucine in 100 grams of pumpkin seeds, and 0.7 grams of leucine in 100 grams of kidney beans.
The Bottom Line on BCAA Supplementation
There is no doubt in the scientific literature that adequate levels of branched-chain amino acids (BCAAs) are vital to building muscle, improving strength, and maintaining lean mass. However, there is little evidence that consuming BCAAs through supplementation is more effective than a high protein, BCAA-rich diet.
That being said, if you are at a low body fat percentage (less than 10% for men and less than 15% for women) and following a moderate caloric deficit or training in a fasted state, then BCAA supplements might be beneficial. I use and recommend CleanMachine BCAAs.
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