What does "having her support" really mean to you? Is it okay if she cheers you on, but doesn't commit as much as you do? Is it okay if she just complains the whole time?
Weight loss is a lonely road, occasionally. It's great to have a friend or family member who goes it with you, but
you can only be responsible for
your choices. Not someone else's. You can encourage. You can be supportive, but when it comes down to it, it's your decision to exercise or choose a healthier meal.
That is why so many people join and participate on 3FC. It's why so many people look for in-person meetings like TOPS or Weight Watchers. Having a support group of people who KNOW what it's like and who are also committed to losing weight is very important. We have to have a place to vent, or find ideas or forge new friendships.
It sounds like your friend maybe isn't as committed to this idea as you are. Maybe she'll change her mind, but you won't be able to "make" her change. Weight loss is a personal journey. Yours and hers are going to be separate even if you do it side by side.
The best you're going to be able to do is to "show by example" just how great eating healthier and moving more are for your body! If you happen to show more progress than she does and she asks how, feel free to briefly explain what you're doing (not complain about what she does) that you've
made time to exercise. That you've
made time to eat healthier. That it's
hard work, but you're
choosing the hard work over
making excuses for yourself.
In the meantime, find yourself some people who DO understand the kinds of changes you're willing to make so you can lean on them. And don't be frustrated if your friend's version of change is different from your own, we all go at our own pace.

You can do this!