You have to stop and think about whether you are truly hungry, or just want to eat. There is something called "emotional eating" which one does as a way of comforting themselves. I would find a therapist and find out why you want to eat all the time. It may be anxiety or depression. Some of us can't eat with this, others find it comforting.
Also, make sure you're not eating out of boredom, and if so it's time to get busy with doing things you enjoy instead of eating. Also try drinking water when hungry to fill up. I am not aware of any medical issues that makes one hungry all the time, other than a tape worm, but then you wouldn't gain weight. Even this may be an old wive's tale LOL. If someone else has an ideas they will post to your question, so stay with us for more advice. In the meantime when you want something to eat, ask yourself "am I actually hungry, or just want to eat?" Take care..
Have you asked your DR for blood tests? if nothing underlying i suggest accupuncture, it really helped to stave my hunger
i usually keep eating to a schedule i also take medications the same way :)