“A lot of male celebrities don’t give themselves the freedom to be who they are, but Nick has grown up, and this is who he is presenting now,” Mr. Hendrich said. “I mean, what can you say? He’s hot.”

Not since the R&B singer D’Angelo appeared in the buff for his music video “Untitled (How Does It Feel)” 15 years ago has a male pop act been so at ease objectifying himself.

No other crooner on today’s charts sells his sexuality as overtly as Mr. Jonas, whether it’s on his personal Instagram account (a belly-button-baring post from September received over 278,000 likes), ripping off his shirt while being interviewed for “On Air With Ryan Seacrest” or paying a visit to “The Ellen DeGeneres Show” with no pants on.

Then there is his burgeoning acting career. He stars in the new DirecTV series “Kingdom,” in which he plays a (usually shirtless) gay mixed-martial-arts fighter struggling with his sexuality. In addition to his many bedrooms scenes, there has been much conjecture about a future scene in which Mr. Jonas may appear completely naked.

“Your body is a healthy thing to be comfortable about,” he said. “And I didn’t only want to talk about being comfortable in my skin, but show people the transformation I’ve made, too.”

Cultural gatekeepers have taken notice of his sexual metamorphosis.

“I had some ambivalence at first because no one can capture how perfect Marky Mark looked in 1992 with that body,” said Mel Ottenberg, a stylist for Rihanna and the fashion director of 032c, a magazine. “But in this era where people’s attention span is zero, if everyone stops and thinks about what you’re doing, you’re doing it right.”