antipsychotic medications bipolar disorder

With newly diagnosed D. Bipolar II (rapid cycling), medication questions?
My psychiatrist wants me to start with lithium, but am very reluctant since it seems to cause a fairly large increase in weight. He suggested some other mood stabilizers and antipsychotics are believed to be weight neutral, but after read some testimonies of what might come through, it seems that all mood stabilizers cause significant weight gain. So my question is, does anyone have any experience and knowledge of medication for bipolar disorder that does not cause weight gain?!
I have been on lithium for 17 years and never had any side effects. The medicines I have taken throughout the year causing weight gain are: Mirtazapine – an antidepressant Citalopram – Antidepressant Olanzapine – Antipsychotics may take several years of trying different cocktails of drugs to find the right one for you and for them to be in a therapeutic level. I've been in my current concotion about 2 years and seems to be working well.
Big Pharma sucks