I usually have to hear things many many times to be convinced and motivated enough to change. I remember when someone first told me about The Zone Diet, maybe 15 years ago, I thought "there's simply NO WAY I could eat that food and not eat all the other stuff that's the staple of my diet". But once I'd heard it enough times, and started gradually absorbing some of it into my diet, I eventually realized it was a good approach. Primal was an easier leap, because it has enough similarities to Zone.
I'm not sitting here, though, wishing that a friend or relative had really pushed me 15 years ago, even in a 100% supportive way. I'm stubborn as an ox, and need to reach conclusions on my own. You've done your part--you've given her info, and now it's up to her. Be VERY glad she's away from you for 18 hours a day, because you definitely do not want to become the overseer of what she puts in her mouth.
And don't feel guilty about HER lack of success!!! You have no control over other people, so how can you be at fault?
Zone diet on and off for several years....worked, but too much focus on exact meal composition
Primal since July 2010...skinniest I've ever been and the least stressed about food