Here’s another: talking frankly about her weight. Ms. Rousey, who is 5 feet 7 and fights at 135 pounds, weighed 153 on this September day. She feels most attractive around 148. “That’s like my favorite weight,” she said. But she still likes to get a little bigger than that, sometimes, because she has to choose between the look of her abs and breasts. “You can’t have both,” she said.

Last year, Buffalo Jeans signed her as a face of the brand. In photos and videos from her first Buffalo Pro shoot, Ms. Rousey looks like the girl next door, if the girl next door were really ripped, smiling playfully while revealing menacing midsection muscles in an unbuttoned denim shirt.

“Frankly, that’s what we loved about her,” said Dari Marder, the chief marketing officer of Iconix Brand Group, which partly owns Buffalo. “She wasn’t supermodel size.”

Ms. Rousey cares about nice clothes. She wore a black-and-white dress with mesh and cutouts customized for her by Inas Couture to the ESPY Awards in July, where she received the best female athlete award as well as the ire of some fashion critics (E! decreed her outfit “more club-worthy than red-carpet ready”). Last week, on Jimmy Fallon’s show, she wore a House of CB dress with a neckline that nearly reached her navel.

She has a wish list of brands she would like to work with, including Helmut Lang (“they fit my body so well,” she said) and Stuart Weitzman. She admires the style of Beyoncé and Rihanna (“I don’t have the same coloring but I have the same outline,” she said). At the Made in America festival last month, Beyoncé gave Ms. Rousey her stamp of approval, playing an excerpt from a tirade Ms. Rousey went on in a U.F.C. video about what she calls “a kind of chick that just tries to be pretty and be taken care of by somebody else.”