Weight gain is a side-effect common to all of the medications you are taking. Olanzapine has the maximum potential followed by paroxetine, valproate and finally lithium. The combination can be worse. You can consult your doctor again and tell him about the weight gain. He will try to reassess the situation and make changes to your dose regimen. You can try adding exercise to your regimen (as per your physician s advice). Have control over your diet also. These medications do increase appetite and having salads for snacks can help cut calories.