I've actually done a lot a research on weighted blankets. I work with therapy center for children and we sometimes use weighted blankets with a few of the children during nap time. The weight is recommended to be 10% of the body weight with a lb or two added if desired. They are made to be small as to focus all the weight on the body and not on the sides. My quilt is (at least planned to be) 3ft x 5ft and 15lbs, and my boyfriend is 5'2 and 140lbs.
My boyfriend loves quilts, he also has aspergers which is my reasoning for weighting the quilt. Since I cannot spend time with him during the summers when school is out, I decided I would "mail him a hug" because I'm just corny like that.