The gorgeous Destiny's Child singer plays Cuba Gooding Jr.'s love interest in the movie, due to be released on DVD and home video Tuesday.
"That's what attracted me to the movie," Knowles told reporters in New York recently.
"I told my agent: 'Don't give me a script with another glamorous person... Because I don't want to do that,'" she explained. "I feel like it was necessary for people to see me heavier. It was necessary for people to see me with my hair twisted and not so glamorous, with no makeup on, no glamorous clothes and for people to see me dealing with real issues that women go through, being a single mother.
"I grew up in my mom's hair salon and I was around single mothers, just powerful women in general, and I could take that and put that in the character, which was nice."