I took Ativan for several years with no weight gain or problems switching.
Before you try Cymbalta, it can also be very stimulating, and there's also evidence being considered now by FDA about liver toxicity, so just be careful out there. Ativan shouldn't be a weight gainer, but it is an addictive med and probably won't be used for you long-term. The weight gainers tend to be the less-stimulating anti-depressants, which are the ones unfortunately used for anxiety. I always say it depends on how badly affected your life is -- if you're still coping okay, therapy and gentler natural techniques and remedies can be tried before you have to turn to medication.
Ask your doctor about Cymbalta. It's one of the new breed of anti-anxiety meds and might be better for you.
The question is: did Wellbutrin work for you in the past? Any experience with Wellbutrin? Wellbutrin is a rather stimulating antidepressant that will not cause weight gain but usually not prescribed for anxiety due to it's stimulating effect which can be strong.
Surely, in my book, benzodiazepines (like Ativan) should be for occasional use and a more proper long term treatment should be antidepressants and counseling.
M4