My experience is like Pookyl's. Weight gain has only been an issue depending on my dose. I've found Seroquel XR to be more weight friendly than regular Seroquel. If I take 450 mg or less, I am fine. Above that and I have to work very hard to maintain and even harder to lose weight.

Sedation can be an issue on both Seroquels. Many people take regular twice per day, people on XR usually only at night. Your body usually adjusts to the med over time so the sedation effect lessens. With Seroquel XR, I do well if I take mine at 7 pm and go to sleep no later than 11 or 11:30 pm at the latest. Otherwise, I sometimes have a Seroquel "hangover".

The goal is to take as much as you need and no more, in my view. Sometimes when I've been stable a while my psychiatrist lowers my dose. That can be good in terms of both the weight gain and sedation side effects. Other times my dose must go up, if I develop a mood episode. My personal favorite dose is 450 mg of Seroquel XR, but it does indeed need to be increased from time to time.