A recent review by Wolfe has been published in the Journal of International Society of Sports Nutrition that adds another layer to the rationale behind ditching BCAA supplements altogether.
It appears that exclusively relying on BCAAs before a fasted training session (a method popularized by Martin Berkhan known as Leangains) doesn't provide any sort of "protection" for your muscles and could very well decrease net muscle protein synthesis (MPS, a.k.a. muscle growth).
By taking BCAAs (leucine, isoleucine & valine) in isolation, you're missing out on the other six essential amino acids that are necessary to build muscle. While leucine has been shown to send the signal to activate protein synthesis by itself, you need the remaining amino acids to build any sort of muscle.
If you're not eating those aminos, which would be the case if you're only taking a BCAA supplement, the rest have to come from somewhere. In this scenario, those aminos would be provided by breaking down your own bodily protein. As Menno Henselmans stated in a post about this same review, "you'd, for example, be breaking down your biceps to stimulate growth in your quads."
Not exactly ideal for muscle growth in the long term.
I'll leave you with the conclusion from the review itself:
"We can conclude from these two studies that BCAA infusion not only fails to increase the rate of muscle protein synthesis in human subjects, but actually reduces the rate of muscle protein synthesis and the rate of muscle protein turnover. The catabolic state was not reversed to an anabolic state in either study. Further, a sustained reduction in the rate of muscle protein turnover would be expected to have a detrimental effect on muscle strength, even if muscle mass is maintained. Muscle protein turnover renews the muscle fibers and results in increased efficiency of contraction at the single fiber level , which is reflected in increased strength in vivo, independent of muscle mass [17, 18]."
In short, stop blindly putting your faith in supplements and eat some real food.
Let's get this out of the way right at the top: supplementing BCAAs in addition to a sufficient protein intake seems to be pointless (1, 2). I can stop writing this post right now, but I'm a nice guy, so I'll explain.
Those two studies cover a pretty wide range of subjects: from non-resistance trained people to competitive athletes; from weight maintenance diets to weight loss diets. Both studies came to the same conclusion that I stated above. So the initial take-home message is to get a sufficient protein intake on a daily basis. 1.8 g/kg bodyweight will do the trick.
However, anyone who's training regularly should already know this, and if you're willfully disregarding this aspect of your diet solely to justify drinking a fruity neon-colored drink while you're training, we have bigger issues to work through. While BCAA supplementation may be somewhat effective if it helps fill the gap in populations that consistently struggle with eating enough protein (i.e. vegetarians/vegans), everyone's top priority should be fortifying their diet with whole, unprocessed proteins first and foremost. Not only can this boost your metabolism more due to a higher TEF, but these foods also stimulate protein synthesis to a higher extent for longer than any supplement could ever hope to.
Here's another point where I can stop writing, but people will surely point to the boatloads of "research" that supports the efficacy of supplemental BCAA, "especially" around training. I used quotes because nearly every study that has found benefit to supplemental BCAA has been operated by or funded by a company that sells those exact supplements. Think they'd have any incentive to make some false claims?
I digress; simply stating this conflict of interest isn't enough to completely dismiss it. So let's tear some of this "research" apart, shall we?
One of the shining beacons of light supporting BCAA supplementation around the workout is Dudgeon et al. (2016). The researchers of this study, which was funded by Scivation (a company that sells a popular BCAA product known as Xtend), concluded that "BCAA supplementation in trained individuals performing resistance training while on a hypocaloric diet can maintain lean mass and preserve skeletal muscle performance while losing fat mass."
In shorter terms: BCAA supplements can help you maintain muscle & lose fat while dieting. In the study, the researchers split up 19 trained males (>2 years of training experience) into two groups; both groups were prescribed a calorie-restricted diet. All subjects completed 4 training sessions per week and were given instructions to eat less on their 3 rest days. The "only difference" between groups was the use of either 14 grams of Xtend pre & post workout on training days in the BCAA group, and the use of a calorie-equated amount of Powerade in the Placebo (CHO) group.
Strength & endurance increased in both groups over eight weeks, so the strength data isn't very conclusive. However, here are the tables describing the dietary & body composition analysis for both groups (CHO vs BCAA):
A few things should jump off the page right away. Both groups had more than sufficient protein intake, which is a good thing. Even if we're relying on dietary recall data, which is notoriously inaccurate, these targets far exceed the optimal protein intake values based on the subject's body mass. Unless the subjects were literally missing the target by 50%, we can say with relative certainty that both groups were getting enough protein.
Another thing that you should notice which is not a good thing: the CHO group was actually a good deal lighter on average (by nearly 13 lbs) than the BCAA group, yet they were consuming 1698 more calories per week on average than the BCAA group. Now, based on the body comp numbers, the CHO group did start the study period with about 1.5% lower body fat than their BCAA group counterparts. The leaner you are to start with, the more calories you can properly utilize in the first place. You have better "nutrient partitioning" due to a multitude of factors, including but not limited to a better inflammation levels, a better hormonal profile, higher carb tolerance, etc. In fact, even with the additional calories for the CHO group, their deficit was likely still too large.
How do we know this? Even though the CHO group was leaner to start with & ate a good deal more calories, they still lost more fat than the BCAA group. Go look at the table again. The BCAA group lost 1.32 lbs of fat on average. The CHO group lost more than double that (3.08 lbs). A higher rate of fat loss in an already-lean population is a strong indicator of an overly-aggressive deficit.
Another hallmark of a diet being "too aggressive" is lean body mass loss. This has been shown numerous times in the research: the leaner you are, the less aggressive the diet should be in order to maintain lean body mass (3, 4). The BCAA group actually gained about .9 lbs of lean mass on average, while the CHO group lost just under 2 lbs. You can gain muscle & lose fat at the same time, as the BCAA group appears to have done, but you must manipulate the deficit very carefully to match the trainees current level of leanness. It is apparent that this was not done properly in the CHO group.
Doing some reverse calculations, the BCAA group lost <0.1% of bodyweight per week (basically stayed weight stable) while the CHO group lost 0.4% bodyweight per week. This indicates that the relative deficit experienced by the CHO group was roughly 4 fold of the BCAA group.
While greater muscle loss isn't exactly a ringing endorsement in favor of the CHO group, know that muscle loss is all but an expectation on a prolonged calorie-restricted diet. Contest-prep style diets can induce nearly 25% loss of lean body mass. This can be considered the "worst-case scenario."
For the CHO group, they lost about 1.3% of their lean body mass. A.k.a. far from worst-case scenario. This again indicates that their energy deficit, despite the higher amount of calories per week, was likely a bit too large to sufficiently maintain or even gain lean body mass.
One final note: the error margins for the weight ranges of the BCAA group are much wider than the CHO group. This means that the body comp data was much more variable in the BCAA group compared to the CHO group, so direct apples to apples comparisons might not even be on target. The way the numbers are presented, this could theoretically mean that someone in the BCAA group started the study period with 76.9 kg of lean mass and finished with 68.3 kg. This is the problem with large error margins; you simply have a higher degree of variability in your data. As such, it strikes me fishy that the margins are just 2.5 kg either way for the CHO group while the margins are nearly double that in the BCAA group.
Anyways, it should be easy to see that the lean mass retention in the BCAA group can't solely be chalked up to the BCAA supplementation itself. At the very least, the BCAA supplement was in no way permissive to fat loss, since the group not supplementing with it lost more fat in the first place. Also, it's much more reasonable to assume that the CHO group was in a more drastic deficit than the BCAA group was to begin with, making the members of that group much more susceptible to losses in lean body mass in the first place. In an ideal scenario, you'd apply the same relative deficit to all subjects; this does not appear to be the case here.
You should now be able to see the flawed logic used to support this nonsense claim of BCAA supplementation. Menno Henselmans has touched on this point multiple times (here & here) on Facebook to try to spread this message. I'm joining the cause.
Leave the fruity powders at home; you're just as well off drinking Kool Aid. And you wouldn't do that in the first place, right?
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