Lyric discussion by tayloradair 

Cover art for Mary Jane lyrics by Alanis Morissette

Everyone has very valid points about this song. What I personally think it means is this: Mary Jane is a girl who is depressed and she's always doing things to please others and not herself. she may be in an abusive relationship or just taking the general abuse of life when Alanis refers to "bruises". She isn't letting anyone help her. "Are you losing weight again.." probably just refers to another attempt for her to be accepted by others.