Interesting that alcohol can be seen as acutely protein-sparing in the sense that it halts oxidation of all 3 macronutrients. Not that it would be a good basis for binge drinking, but good information to know.
Question: You posted a link to Matt Stone's post about low-carb diets and lowered metabolic rate. I am wondering if metabolism is more affected by glycogen levels themselves or by the mere act of eating enough carbs to prevent the drop in thyroxine output.
1) What if I ate 150g of carbs prior to a completely glycogen-depleting training session? Would my metabolism still drop due to low glycogen? Or is it the fact that I ate enough carbs for the day that would prevent the drop? In other words, what if I did the training session first, followed by consumption of 150g of carbs? Now, those carbs would go toward glycogen resynthesis.
2) Does the makeup of the carb matter? What if out of 120g of carbs I ate in a day, 50-75g of it was fructose? Now hepatic glycogen may be full for a while, but that doesn't leave much for muscle glycogen. Which glycogen tank is more intimately linked to the CHO-T3 axis?