Muriel's Wedding....
http://www.imdb.com/title/tt0110598/
Such a cheesy ABBA filled movie(I LOVE ABBA). My obese aunt and I found this movie just after high school and FELL IN LOVE with it.
It is a story of a young woman who is over weight, insecure, and unkempt. She starts out basing herself worth on her dating and getting married. Ends up loosing weight, getting fit, finding her self and realizing a man DOES not make who you are.
Like I said, this is a low budget, cheesy film, but it is one I always recommend for a good look at self worth, and ABBA filled fun =)