I Was Just Prescibed Latuda. I Was On Effexor (225

I was just prescibed Latuda. I was on Effexor (225 mg) for 20 years. I weaned off the Effexor for 1.5 years and became depressed, loss of appetite, confused, insecure...I also lost 20 pounds of which I am not willing to gain back. My psychiatist and I have been working on med since February. I am a met met with bipolar 2 disorder.
What are the chances of weight gain on Latuda. 30 mg per day. I have no other health conditions. I am 59 years old. Please advise and thank you.