From my understanding, this is Martin Berkham's reasoning for fasted training + pre-workout BCAA intake.
1. Fasted training upregulates myogenic transcription factors, with the greatest effect being on p70s6 kinase, versus fed training. This means that amino acids ingested post-workout will be shuttled into the muscles faster. This may have to do with high carb intake pre-workout or high insulin levels interfering with gene expression necessary for anabolic adaptations.
2. Fasting is catabolic. At about the 16 hour of fasting mark, through gluconeogenesis your body is oxidizing 50% fat and 50% protein. As a compensatory mechanism though, protein synthesis is upregulated per #1.
3. "Pre-workout protein blunts cortisol throughout the day, which is another effect not seen fasted or with carbs only. In this context, lower cortisol could boost metabolic activity of muscle protein synthesis by allowing it to go on unscathed (cortisol increase protein breakdown and decrease synthesis)."
4. "Older studies show that consuming pre-workout protein increase protein synthesis far more effectively than pre-workout carbs. This effect is due to shuttling amino acids to the working muscles, which in turn may increases protein synthesis for up to 48 hours. It goes without saying that if no dietary amino acids are present at this time, the effect would be blunted, which is what occurs if one would work out completely fasted or with carbs only."
5. "I argued that the need for pre-workout protein intake was due to this being a case where the benefits (increased protein synthesis) simply outweighted the negatives (insulin increase; low insulin being a determinant of the fasting state). It's also known that BCAAs independently affects the same myogenic pathway through which fasted training may increase protein synthesis in response to post-workout nutrition." ***This is the double whammy p70s6 kinase he talks about in one of the links I posted.***
"With BCAA you get the aminos needed for protein synthesis without the insulin and caloric load brought on by whey protein. Low insulin = the fasted state. You pretty much answered your own question in that you would have to consume 40 g of whey to get the same amount of BCAA I recommend (a recommendation based on a study where 10 g elicited the maximal effect). Then again, one could question what the real world implications would be in comparing whey and BCAA in this context. I hardly doubt this is a deal breaker in any way. Then again, if you wan't to optimize everything, BCAA is the way to go."
6. "The higher REE observed in the protein-supplemented experiment can be explained by increased muscle protein synthesis, which is a metabolically costly process." ***REE = Resting Energy Expenditure***