I have moved from lithium carbonate to zyprexa (olanzapine) for bpd and my hunger is unending. What is the best thing to do to keep weight off and lose it too?

You are not alone. A number of these newer medications have this effect, and it can be very challenging to overcome. You and your doctor should weigh the benefits and costs of this med: does it work so much better for you than all the alternatives? If not, consider trials of some others. If it is a must, then an organized weight control program, supervised, may help. There are no quick fixes, alas.
Zyprexa (olanzapine) . Weight gain is very common for these medication . To limit that watch what u eat , how much u ear and exercise.