I figured I would ask you scientific people about one thing I don't really understand about insulin resistance at night.CBL book told me that the fat and muscle cell get insulin resistant in the evening, so the other cells have to be to one cleaning up the carbs you eat at that time (unless you do some resistance training). However, since I'm trying to bulk, the advice is to still backload on off-days, which I do happily.I'm going to quote the CBL book here :

and as the evening approaches insulin sensitivitywanes. Introducing too many carbs into the system at this timecould mean metabolic chaos. Ah…but wait: there’s a way to makemuscle cells soak up carbs even if insulin sensitivity tanks.Resistance training.

So what happens then, how does my body deal with all those carbs on off days? I know it makes me feel somewhat lethargic which is probably because the brain and other tissues that contain the always-on GLUTs have to do the work. But do the fat and muscle cells also help at least a little? And if not, then what is the point of doing it at all?

Your muscle and fat cells still do nearly all of the glucose clearing.  If you are resistant training and have room in your glycogen stores, the carbs should go mostly to your muscles.  If you have full glycogen stores, then you shouldn't even backload.Most people don't need off day backloads even on DB.  I would see if you can get away with not doing it, which most likely you can.