This seems to happen to many of us who have had surgery for UC. I, too, was lighter when I was sick and then after surgery I put on about 30lbs over a course of 2 years. I let it slide until this year and I have now taken off about 24lbs. Once the body is healthy it's harder to lose the weight! No magic, just reduce calories and increase exercise.
dx proctitis in 1987
dx UC in 1991, was stable until 1998
1998 started prednisone, asacol, pentasa, nortriptylene, ativan, 6MP, rowasa enemas and suppositories, hydrocortisone enemas, tried the SCD diet, being a vegetarian, omega 3s, flax, pranic healing, yoga, acupuncture, probiotics
2000 lost all my B-12 stores and became anemic
2001 opted for j-pouch surgery- now living life med-free