Hi Lisa, I too have been on Lexapro since March, and it worked great for my depression and anxiety, but I stayed hungry and gained weight too. I just started on Wellbutrin XL a few weeks ago, and am just now adjusting to it. It took a little while, but just in the last couple of days, I can notice a big difference.
I lost 4-5 pounds while on Wellbutrin; I think it is typical to lose a little weight or at least stay the same since it is in a different class of drugs than the SSRI's. I was on it for depression, but I also had anxiety and in the first few weeks the anxiety got noticably worse - I had some of my worst panic attacks during this period. I stuck it out, and eventually the depression got better along with the anxiety.
You might also want to try 5HTP - it is an amino acid that is effective against depression, and it is also helpful as a weight loss aid. I've used it and it does help, with no side effects. GABA is also useful for anxiety. You can do a search to find out more about these.