I've struggled with weight gain since my resection last year. Prior to that, I was maintaining but slightly overweight. Now I'm steadily gaining without much explanation.
My GI said most of his patients have the opposite problem and he's not sure why I'm gaining. I wonder if my system is processing food differently now that it's been reworked but I'm no doctor. =)
It's very frustrating. I'm going to start a more limited diet and food journal for awhile and see what happens.