Some advice???

My 10 year old niece has a body issue. She thinks she is fat, and she weighs only 100 lbs. She does have the large hips and butt, but they complement her. She doesn't see it that way. I took her to the mall this past Saturday, and it took us several hours to find a pair of jeans that she could wear. Right at the end, I found her in the dressing room crying her eyes out. Her self-esteem is shot; with all the pressure now of being ultra thin, she thinks she is an elephant. I have tried talking to her, and reassuring her that she is beautiful, but all my advice falls on deaf ears. Her mother could care less about her daughter's problems, and I am the one left to relift her. Does anyone have any advice on this subject. I have tried and cried so many times. It hurts me so bad to see her hurt like this. I am at a loss of words that might make her feel better.

My son had these same issues when he was younger. With her being a girl I would explain to her that what she sees as "fat" now will be nothing but gorgeous curves in a 5 or 6 years! I would stress to her that she is only ten, and nowhere near as tall as she is going to be. I would also point out that children are are usually heavier around this age because they are gaining wait for puberty. I have no idea if this is true but have heard it several times. I would get her involved in a group activity to maybe take her mind off of it. Sorry I dont have more ideas.