Weight gain with paxil

I just started taking Paxil yesterday, I was wondering if anyone has had a loss of appetite, but still gained weight while taking Paxil? About how long did it take before anyone started to notice weight gain? I'm really nervous about taking this medication. My doctor put me on 20mg Paxil, but I'm only going to be taking it for one month, until a psychiatrist can prescribe me something else. I don't want to gain any weight, I've been trying to lose weight. Any advice would be greatly appreciated.