Could an eating disorder be related to bereavement after losing someone?

Yes : But not in the way you would normally think about it. Grief and loss can be very powerful emotions. If you were trying to fix the feelings with food then this is emotional eating. If you continue to try to fill the emptiness with food then this can become a problem secondary to the grief itself. Treat the grief first by finding a good therapist who specializes in grief and bereavement. Many people.