For any medication try and note a specific connection that is weight gain associated with taking the medication for at least a week or two. If your weight gain started prior to the medicine, it is unlikely that the medication is a significant contribution. It is important to be realistic in this area. This is related to fluid retention for a variety of reasons. One is a high level of salt intake, which can be corrected by monitoring your total sodium intake and keeping it below 2,000 milligrams per day.
Medications containing estrogen like birth control pills also can increase fluid retention.
As well as medications like Lithium that influences water balance in the body. I am looking for documents about eating habit regarding daily frequency and time. They will have abundance of information. Also, call your local county department of health. They should be able to send you some useful materials.