The difference between average movies and great movies is not budget, nor actors, necessarily. It doesn't even have to do with the story being told.
The difference has to do with how you tell the story.
There are many weight-loss stories out there; and there are many fat-person-as-the-butt-of-the-joke stories. There are many coming-of-age stories; there are also many stories of individuals conquering personal goals despite many odds. Incidentally, there are also many martial-art/inspirational movies out there. But even if you were to artfully mix them all up, I don't think you could come up with a movie as thoughtful, funny and unique as "A Matter of Size," a movie I had the pleasure of seeing last week.