My mother has suffered with crohns for 20+ yrs and she has it really bad. In 2005 she had 90% if her colon removed and her small intestine. She also had to have a ilostomy bag for 4 months and have the surgery reversed. She has been on prednison(spell check ) since and that's the only thing that keeps her going, although its very dangerous to be on it long term. She also has to take pain meds daily and her body can not go without. Her weight is constantly up and down and she can't tolerate food well without rushing to the bathroom. She never know when she's gonna have a flare up but when she does its horrible! at least 30+ stools a day and she always ends up in the ER. There some of the docs treat her as if she's coming for pain meds which really upsets me. I hope your situation isn't as bad but if so I'll keep you in my prayers as well.
I struggled to understand your interesting question.
You had ulcerative colitis and had to have your colon removed as treatment. You had an ileostomy bag for 6 months and then had anastomosis to take down the ileostomy. This is better than when you had colitis and had to go to the bathroom 30 times a day, but now you keep gaining weight. Starchy calories absorb seemingly instantly, unlike when you had malabsorption. You seek a solution.
Right?
I think you need to realize your body is much more efficient now. You have to limit calories and optimize nutrition. You should see a dietitian to get help with this.