I have no experience with zyprexa but my pdoc told me seroquel is basically a 50/50 chance of if you will have the weight gain side effect or not. I am on 400mg of seroquel and luckily I have not had an increased appetite or weight gain. My pdoc did tell me that if I did have a weight gain problem on seroquel, there are medicines he could prescribe to help curb the appetite.