Croc, it's plagued me for a long time now (had mine out 2011), I never had a prob losing weight, always came off pretty easily and quickly before then.
Started Slimming World not so long ago, yet can't even shed a pound 
Mucho research online, apparently the gallbladder stores the bile to break down fats, however, w/o the gallbladder, the bile is instead stored in the liver, but does not work as efficiently as it would do in a gallbladder, and therefore more fat being stored 
I went to my GP about this, as I'd always been a slim, size 8-10, then after babies, probably 10-12, but since 2011, after surgery, I can't shift from a 14, and was crawling up to a 16. I'm fuming actually because consultant never mentioned any of this, but Google it and it's literally all over the Net 