Uh, at 14 she's hardly done growing. I didn't stop growing a lot until around ~18, and even after that I added an additional inch or so before I was 21.
VLC is ridiculous at any age, specifically that young. Expect her to struggle in all aspects of life on that diet at that age.
When I was a teenager I ate even more carbs than I do now probably, and I couldn't imagine how bad I'd feel restricting my diet at that age. If my mom tried to control what I ate, I'd rebel and just eat at a friends house and sneak junk food all over the place. Have her eat her fill of fruit, and other starches, it really doesn't matter at that age. No one should be dieting, your metabolism is at its peak anyway.
Time is passing so quickly. Right now, I feel like complaining to Einstein. Whether time is slow or fast depends on perception. Relativity theory is so romantic. And so sad.