Running will burn calories, and squatting makes your legs and butt stronger, but if you don't run a deficit you don't drop weight and if you run too much you can end up skinny-fat. Running can also overstimulate appetite, and if you run while gaining weight it PILES onto your legs as the body stores more and more fat near the working muscles. And if you run while you're still quite heavy, you can cause your body a lot of grief from the heavy pounding as your feet hit the road.
ANIMALHOUSE, I may have been too quick to judge though - if she's not VERY heavy, not dieting too hard (but IS dieting) and not doing too much running she'll be fine. Not the method I'd chose, but I'm lazy.

The friend you are helping - she's not very heavy to start with - just needed to tighten up a bit?