Seroquel is usually prescribed at 300-400 mg. in split doses, 2-3 x/day (ie. 150 mg. in the AM, 150 mg. in afternoon, and 150 mg. in PM). Let your doctor know about the weight gain. Sometimes a doctor can cut back the dose and prescribe a mood stabilizer in conjunction with the seroquel. Mood stabilizers may help level out the increased appetite. Ask your doctor about this. Hope this helps.

I took 800mg per day. Tiny dose in a.m. & rest at bed. Was hospitalized once & they gave me 900 mg (which I believe exceeds FDA guidelines).
Was already overweight so that wasn't an issue, no additional gain at least. I also experience psychosis both with depression and mania.
Please keep your caregivers informed of any and all changes in weight or otherwise. I took it for a couple of years.