Encouraging a Friend to Join?

theunimpossible

I just joined, and I've been using MFP for about a week, I find the community to be very friendly and helpful!

One of my close childhood friends, is obese, and she is undergoing kidney problems, (dialysis).
She is waiting for a kidney transplant, and has a very restricted diet. She has always been overweight, I think she's at an all time high. Her parents, worry about her too, I've been told that she is always buying food without her parents knowing and I've been told that she's eatting beyond her restrictions.

I really worry about her health, I want her to join, without seeming too conceded about it. My weight actually lies within the middle of the healthy range, so I don't want to come across as calling her "overweight", and making her join this site.

How should I go about encouraging her to join the site? How should I approach her?