Great post! The first study was very interesting, particularly in the older adult rats demonstrating that CHO had greater anabaolic effects post prandially than the fat.
Im curious as to what you guys think the mechanisms of each are. I think clearly insulin effects protein synthesis via a PI3-K-AKT-mTOR mechanism, and also via its ability to increase endothelial NO and thus skeletal muscle blood flow. So when combining carbs with amino acids the carbs should amplify the amino acids effects. And of course we know CHO has big time effects on protein breakdown.
Fats on the other hand arent so obvious to me. For one they may elivate certian anabolic hormones such as testosterone, and secondly it is possible that just by virtue of added substrate that they may spare the oxidation of amino acids