Overeater symptoms and conditions

I am going to begin taking 25 mg of Topamax at bedtime tonight. After reading all of these posts I am a scared. I was prescribed Topamax for bipolar disorder. I am currently taking Lamictal as well. I always gain weight on psychotropic drugs and need to lose about 15 lbs (all of which I have gained over the course of being on Lamictal). Any who-my psychiatrist said that this medication may help counteract the weight gain I have experienced. Although I do not consider my self an overeater now. I do hope that it helps me to not like the taste of sodas though. I am addicted to Mt. Dew and caffeine, which I wouldn't mind stopping. Anyway, I am supposed to increase my dosage by 25mg per week until I reach 75mg per day. I am also supposed to go back and see my doctor before I increase the dosage beyond 75mg. I just hope I do not have the horrible side effects I have read here. Some of them I know I can deal with especially if they are temporary but the anxiety/depression/shortness of breath/lack of energy/morbid thoughts are the main ones that concern me. My psychiatrist said that with this medication I should drink plenty of water. He said that it could cause headaches and other side effects if I'm not sure to drink plenty of fluids with this medication. So, I am planning on hydrating myself really well today before taking it this evening. I'll post back and let you know how the side effects are going. Is anyone else on a combination of Lamictal and Topamax or on it for bipolar disorder? I'd like to hear more of your experiences.