my body, which has decided to *gain* weight on an almost exclusively-veggie diet (go figure)

As I understand it (and I'm the farthest thing from a nutritionist), when you lower your caloric intake, the body reacts by becoming more efficient and storing more energy -- going into "famine mode" as it were. So dieting often causes a temporary weight gain -- at least until it "gets used to" the new regime. But how long this takes, I have no idea.

How long ago did you change your diet?