Will the hunger and weight gain decrease after some time, say a few weeks of using mirtazapine?

Often not: Mirtazepine (brand name remeron) is an unusual antidepressant that is sometimes also used as a sleep-aid because it is so sedating. While it is free of some side effects common to other antidepressants (sexual dysfunction, jitteriness), it is well-known to cause significant weight gain. Weight gain usually plateaus (levels off) after a while, but it's hard to lose the weight while on the med.