I'm with you on the mental illness being the worst... But I can tell you that despite my great trepidation of weight gain (I gained 75 pounds in 10 months on Depakote, for ex), I've been very pleasantly surprised vis-a-vis Lithium. Make sure to just drink water and not sugary beverages (nor caffeinated ones) when you get thirsty and it can actually help you lose a little bit of weight. Another tip, take more in the morning and less at night bc then you'll get up less at night. Before I inverted, on a higher dosage at night I woke up as many as five times per night! Now I'm down to twice a night (and I take 1500 mg/day). Good luck!