Thursday, January 13, 2011

Lower Protein to Carb Ratio Impairs Akt/TOR Signaling Pathway after Fasting in Rainbow Trout

"Boy, you need your carbs post workout!" This cornerstone of conventional bodybuilding wisdom is crumbling and a new study, if it had been done in humans, not in rainbow trout, would potentially refute this myth once and for all - at least, if one follows the popular (but false) assumption that it is because you are in a carb depleted or overall fasted state after a strenuous workouts.

A group of European scientists (Seiliez. 2011) investigated the effect of diets with different protein to carbohydrate ratios on the Akt/TOR Signaling Pathway after fasting for 48h. What they found contradicts conventional wisdom:
Activation of the Akt/TOR signaling pathway by refeeding was severely impaired by decreasing the proteins/carbohydrates ratio. Similarly, post-prandial regulation of several genes related to glucose (Glut4, glucose-6-phosphatase isoform 1), lipid (fatty acid synthase, ATP-citrate lyase, sterol responsive element binding protein, carnitine palmitoyltransferase 1 and 3-hydroxyacyl-CoA dehydrogenase) and amino acid metabolism (serine dehydratase and branched chain α-keto acid dehydrogenase E2 subunit) only occurred when fish were fed the high protein diet. On the other hand, diet composition had a low impact on the expression of genes related to muscle protein degradation.
So, not only did an increase in carbohydrates negatively impact muscle protein synthesis stimulated by the Akt/TOR signaling pathway, interestingly it also failed to reduce muscle protein degradation, which is the second reason people use in favor of a high carb meal after workouts (/fasting). 

For people following the research and writings of low carb proponents such as Mauro di Pasquale these results may not be surprising. However, before flushing your weight gainer down the toilette, you should really reevaluate your personal and training goals. For an athlete whose exercise bouts are long and frequent, carbohydrate repletion may well turn out to be beneficial. If not for muscle growth, then for performance maintenance. A general demonization of carbs would thus be similarly inappropriate as the "fat scare" of the late 20th century. It all depends on who you are and what your athletic and aesthetic goals are.