not sleeping enough is a real bitch man.
When I was in that 'sleepless zombie' phase of college, I was taking Power Drive at least once a day, it helped a LOT to keep me going.
As far as getting fatter and putting on weight...
I think Nate Dogg hit it on the head by saying that it gives you more time to eat, which can bite you in the butt.
Also, weird sleep patterns effect hormone levels, it's something to look into.