I have a best girl friend who is that height and she's at 230 lbs... yet she is a doll of a friend to me. She is trying to lose the weight, but there's so much more to it than just losing it.

I admire your efforts to change food choices and such, keep to it. One healthy meal won't change anything, just like when you're thin one heavy meal won't make you fat.

I know guys aren't usually into talking indepth about problems, so maybe she needs a therapist to help her feel good about herself?

Often, therapists don't even address weight issues, but do address the self esteem instead. Once someone begins to feel good about herself, she has the motivation and energy to enact the changes that result in physical health also.

Try to see past her weight, and really make a plan to boost her ideas of herself. You probably will have to do some back peddling, since you've already made it an issue, but keep going, it's the right path imo!