Cosmopolitan" class="x-large" credit="Courtesy Hearst Corp." src="https://adage.com/images/bin/image/x-large/20160208_COLESJOANNA_Cosmopolitan_3X2.jpg" url="" />

Joanna Coles won't hear arguments that Cosmopolitan has been diminished, watered down or become one of many in the crowded space of female-focused media brands.

"The core DNA of the brand ... remains as essential now as it did 50 years ago," said Ms. Coles, editor-in-chief at Hearst Magazines' Cosmopolitan since 2012 and Ad Age's 2015 Editor of the Year. "Some brands come and go, but Cosmo is still very much in the ascendancy, I think, as women's lives open up."

The barrier to entry for new content shops is low, but that doesn't mean these would-be Cosmo competitors have anything to say.

"They don't have a consistent voice, or the voice is the voice that the advertiser wants them to have," Ms. Coles said. "You can't back-engineer a brand. You have to have a thought. You have to have an idea."

Ms. Coles called herself Cosmopolitan's "brand steward." In that vein, Cosmo has been an eager participant on new platforms for content and conversation like Snapchat. (Ms. Coles recently joined the company's board.)

"The different iterations of the brand still speak to the same values," she said. The magazine's audience across print, desktop computers, mobile and video grew 13.3% last year, according to the Magazine Media 360° report, compared with the industry's 7.1% increase.

While she's often praised in profiles and decorated with awards, Ms. Coles made a simple request to this reporter: to not make it seem like she's solely responsible for Cosmo's success (or, in her words: "I don't want you to make me seem like a megalomaniac.").

"It's a massive team effort," Ms. Coles said.

But she has to be careful about singing the praises of her employees too loudly, so as not to lose them to Cosmo competitors. "I feel like I am under constant siege because everybody is trying to hire my staff," she said.