I agree w/ the above poster that said that Seroquel can be responsible for significant weight gain.

I too have taken Lithium w/o weight gain, but that still might not be an option due to your other concerns.

Some people find an antipsychotic, like Seroquel, adequate to control swinging and cycling. If that is not helping, maybe your pdoc can switch you to another AP rather than adding something new (lots of people like abilify). It doesn't work for everyone, but it works for some.

Good luck!
EJ