I just started on prednisone recently for ulcerative colitis. I'...

I just started on prednisone recently for ulcerative colitis. I'm a 20-year-old female college student. The prednisone seems to be working great for the ulcerative colitis. I've been kind of nauseous. My question is this: I've heard that one of the side effects of prednisone is weight gain. However, I've been so nauseous that I've lost weight. The strange thing is that event though I've lost (a small amount of) weight, I *look* fatter, especially in the waist. And it's not all just oversensitive-young-woman's body obsessiveness; even my pants fit kind of tight in the waist What's going on? Is this water retention? Is there anything I can do about it?