10/21/2008 AT 08:00 AM EDT
reclaimed her bootylicious curves (and then some!) to play soul singer Etta James in the upcoming film Cadillac Records
"I gained almost 15 pounds to play the role," Beyoncé, 27, says in the November issue of In Style
. "It was way easier – and tastier – than having to lose so much weight for Dreamgirls
Her legendary role didn't only affect her figure, but it also rubbed off on her music. "Lyrically, it's deeper than what I've done before," the singer, who recently debuted two singles
, says of her album due Nov. 18. "I wasn't mature enough or old enough, or in touch with myself enough, to do this type of album before. I didn't have the guts."
It was only last week that the stealth newlywed opened up
about her secret wedding
to longtime love Jay-Z. "This is a new chapter for me," she says. "I'm terrified, but
excited. It's like I'm a new woman."
2007: Beyoncé flaunts 'Most Beautiful' curves
2006: Beyoncé loses her curves! RELATED GALLERY:
Read about more shapely stars on the covers of PEOPLE!