We used budesonide instead of pred for Spencer, our IBD dog. He had already lost 20 lbs and had no more to lose. Budesonide targets the gut and avoids the wider-ranging side effects of pred, so no weight loss at all. The only side effect we saw was fur loss on the legs and chest over time (three years).
He also had a permanent case of hookworm that did a lot of damage before it was caught. But before the IBD he got a long case of SIBO, in his case a vast overgrowth of two strains of Clostridium perfringens. That tends to kill intestinal tissue and leads to intestinal malabsorption. It can be fatal. So I don't really advise going to an immunosuppressant of any kind, whether budesonide or pred, until you've had a fecal *culture* (culture and sensitivity) to rule out bacterial overgrowth. Otherwise, you're just giving the bacteria a helping hand, you know? (Vets don't seem to do fecal cultures readily, partly because they expect to find many bacteria occurring naturally. It's the *number* of specific bacteria that's important to find out, that determine an overgrowth. We finally had to just order our vet to send it to the lab and get it done!) It took three antibiotics to clear the SIBO. By that time he had developed IBD, and we treated him for that.
Good luck. Let me know if I can be of any help.