Obesity may affect muscle insulin sensitivity via adipose tissue mechanisms or increased intramuscular lipid content.

“one possibility I guess is that there's something that happens to adipose tissue when you store whatever for that individual is an excess amount of lipid that's producing another molecule or some other mechanism by which muscle is affected with regard to its insulin sensitivity the other possibility which I think again many people think is at least partly relevant is that when you increase the amount of lipid in your adipose tissue you also increase the amount of lipid in your muscle”