As you have seen for yourself there is not a connection between multiple bowel movements and weight loss. In fact people with very bad symptoms can also be overweight, some are underweight and many look normal even when their UC is terrible.
That is one of the difficult parts of this disease.
I doubt your weight gain is from your surgery but impossible to know.
Thyroid could be part of weight gain. I knew a woman who had trouble with her weight and once she got her thyroid "fixed" she lost the weight. That was many years ago and I never knew the details and she didn't have UC.
I don't have answers for you, just suggestions to remove sugar from your diet, which helps lower inflammation all over your body as well as lose weight. Become more active, exercise, walk, start slow and keep it up. This will help your UC symptoms too.
Post Edited (imagardener2) : 12/13/2017 4:26:42 PM (GMT-7)