Benefits of BCAAs
If you follow the bodybuilding community, you are probably aware of some of the benefits of branched chain amino acids (BCAAs). That's because they are known to have positive effects on muscle growth and recovery. (See for example Nutraceutical Effects of Branched-Chain Amino Acids on Skeletal Muscle, and Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise.)
Less well known is that BCAAs have favourable effects on the brain, in particular the glial cells (brain cells that aren't neurons, are more numerous than neurons, and turn out to be essential for supporting neurons — it seems probable that most brain afflictions are caused by problems in the glial cells). The beneficial effects of BCAAs come from their important role in the manufacture of neurotransmitters, and vital metabolic cycles such as the leucine-glutamate cycle.
Here are a couple of examples of beneficial effects of BCAA supplementation on the brain: Dietary branched chain amino acids ameliorate injury-induced cognitive impairment, Branched-chain amino acids may improve recovery from a vegetative or minimally conscious state in patients with traumatic brain injury: a pilot study, Recovery of brain dopamine metabolism by branched-chain amino acids in rats with acute hepatic failure..
The problems being helped by BCAA supplementation are similar to some of the benefits that have been shown to be helped by ketogenic diets, and this is no coincidence.
One important effect of keto-adaptation is a dramatic increase in circulating BCAAs.
This fact is one the many proposed mechanisms of the anti-epileptic properties of ketogenic diets. (See also The ketogenic diet and brain metabolism of amino acids: relationship to the anticonvulsant effect.)
There also appears to be a bit of a feedback loop, in that supplementing a ketogenic diet with BCAAs can itself increase ketogenesis relative to the same amount of other proteins.
Nonetheless, the important point to take away from this post is that a ketogenic diet itself achieves what others are striving for by ingesting expensive (and, frankly, revolting-tasting) powders. Therefore it is quite plausible that in addition to the more-studied positive nervous system effects, a ketogenic diet will improve muscle growth and recovery relative to a glycolytic diet, something already anecdotally reported.