Just some personal experience with eating overnight:
Last year I started a job that required me to work three nights a week, 6 PM to 6 AM, the dreaded "Midnight Shift".
What I've found is that I can put on weight so much easier than I ever could before. Since starting this shift in April of 2000 I have gone from 155 lbs to 170, without any training or a bodybuilding diet of any kind (been on hiatus for a while). Sure, most of that is fat, but it's dispersed and not localized in my gut or anything. Since last May I have been training again and eating properly but I think it's safe to assume that eating overnight will definitely make the weight "stick", or will slow down your metabolism.
Reversing my eating schedule during those two days I'm daysleeping has made a huge difference in my metabolism, and I am an ecto who could eat tons of shit and never gain a pound. Just changing my eating schedule has made a ton of difference for me.
I know this is borderline topic here, but if you really wanna bulk, try reversing your eating/sleeping schedule for a couple days a week!