It's different for everyone and it also has to do with where you are starting from... To summarize, for me, in lb:
post prednisone: 150
pre-surgery #1: 110
pre-surgery #2: 135
pre-surgery #3: 120
So as you can see my weight has been all over the place in the past year and a half... I could NOT gain weight to save my life (it's a figure of speech but kind of true!!) during the worst of my flare before my surgery. I ate and ate and ate all day, only the foods I could tolerate (white grains and boiled chicken), and just kept losing weight until I hit 110, my all time lowest weight since reaching my adult height at age 12. I also had quite a round belly from being on prednisone for so long, so my limbs were skeletal while I kept a thick pad of belly fat (plus fat in my face, but that probably didn't weigh very much).
After surgery #1 I tapered off the prednisone pretty quickly -- the belly and face fat went away but at the same time I gained back weight all over, steadily for the next four months while I had the end ileostomy. I gained 25 lb in four months so I guess that's about
1.5 lb per week. With the end ileo I was finally able to eat a variety of foods without pain and because almost all of the small intestine is left intact, I had no issues with absorbing nutrients and calories from the foods I ate. I had a surprising amount of energy and was able to go running a few times a week during this period.
While I was in the hospital for surgery #2 I lost a lot of weight, and I kept losing until my takedown. A large amount of small intestine is taken "offline" during surgery #2 -- the part that is used to make the j-pouch as well as a few feet that are "downstream" from the loop ileostomy -- and as a result my digestion became very fast. Basically like having diarrhea all the time. I took a lot of loperamide (Imodium) but I still felt weak and tired most of the time and it seems I just couldn't absorb the calories or nutrients I was taking in. I ate like crazy during this period and didn't exercise (didn't have the energy), but I still lost some weight and went into the hospital for takedown at 120.
Since takedown I feel like things have stabilized. I have way more energy than I had before the last surgery and I feel, instinctively, that I am absorbing the foods I eat much better. I have less diarrhea and I don't have to take any bowel slowers like Imodium. I feel that I eat normal healthy portions now (instead of wanting to stuff my face all day) and I have enough energy to exercise 3-4x/week. As an aside unrelated to weight, that keeps me mentally healthy too
I don't know when or if I will return to my pre-UC weight. I am a bit of a special case because I was a serious weightlifter before I got sick, and a lot of the weight that I lost was muscle, not fat. I don't know if I will ever go back to that level of weightlifting or that amount of muscle -- although I enjoyed doing it, I always did it with my health as my #1 priority, and I think the hernia and prolapse risk now outweigh the benefits of being super strong.
dx'ed UC pancolitis 5/12
past meds: asacol hd, VSL#3, apriso, rowasa, xifaxan, 6mp, cortifoam, pentasa, cimzia, canasa, butyrate, flagyl, cipro, prednisone, remicade, methotrexate, cholestyramine, cortenema
current meds: none!
step one: colectomy, end ileo 1/16/13
step two: j-pouch construction, loop ileo 5/1/13
step three: takedown 7/31/13