The movie is all and all.....meh.....OK i suppose, not great, not terrible, but the biggest issue is the protagonist who we are supposed to like and root for and i found it almost impossible. Despite the arc of her character basically going from a nasty fat girl, to a nasty less fat girl, to a "nice" girl, it felt forced and superficial. Moreover, by the time she ultimately becomes nicer, the movie is easily 80% done, so it's kind of baked in the cake at that point to not be sympathetic to her or her "plight".
Also, as a runner, the running segments and training was laughably done. Not a big deal, but it was a joke.
If you are into running and want to see a good movie the Barkley Marathon Documentary is great. This, not so much.