A good place to ask this question where there would be a majority of people with experience with mental health medications would be our mental health forum.
My personal experience with anti-depressants is I have always had to watch my diet closely to avoid weight gain with them. Not everyone experiences this side effect and not all anti-depressants have it. It has been several years since I have tried Cymbalta so I can not remember if it was a specific side effect or not.
Sorry I don't have a better answer.