I've always been an obese crohnnie. I think it all depends on where the disease activity is. From my research I've discovered that the small intestines is where nutrients and calories are absorbed and the colon is where moisture is absorbed. Hence, if disease is mainly in small you lose weight, since mine was in the lower half of my colon I just had "d".
I don't know if my understanding is correct but it makes sense in my case. I sometimes think that you are correct about weight gain though. But I think it is more of a matter of metabolism too. I've never been a big eater and I only lose weight if I eat less the 800 calories a day. If I eat more then 1000 I'm bound to gain weight.
Vicky / 48 years old
DX'd with Crohn's during a resection August 2006
DX'd with Steriod induced Diabetes November 2006
Considered in Clinical remission but have minor signs of disease activity
Daughter (27) also has Crohn's since she was 12.
Currently on 4000mg of Pentasa only for Crohn's
No longer able to take 6-MP because of Bone-Marrow Suppression
Cymbalta, Metformin, Lipitor