What happens if you over-express GLUT4 in fast twitch muscle?
( for the record, the over-expressing mice appeared to have about 150% increased basal and insulin-stimulated GLUT4 expression )
Answer: You get a mouse that eats 45% more food than controls but weighs slightly less than them aswell! Not only that, the over-expressing mice seemed to be quite fond of exercise, with a reported fourfold increase in voluntary wheel running.. So........... theres something about disposing of alot of glucose into muscle that makes you want to move.
This really makes me wonder about the association of obesity and laziness. Reduced GLUT4 on muscle partitions calories towards FAT. We could hypothesize here that the reduced GLUT4 on muscle not only makes you lazy, but fat aswell. Its a double whammy.
I recently posted how, some weeks ago when I re-started melanotan-II injections, I seemed to recover a surge and urge to move, and even found the motivation to start going to the gym again. And well, we saw in the last post that melanotan-II / MC4R signalling in the brain dramatically increases GLUT4 on muscle. It all seems to fit together. ........atleast in theory.
Another correlation here is obese people have reduced secretion of GLP-1 in response to carb ingestion, and GLP-1 potently facilitates glucose disposal in muscle.