Watch: From BSB To The Biebs: Keep Your Shirt… Off!

Justin Bieber may be flaunting his bare chest more than usual (and getting flack for it… remember Olivia Wilde’s adamant Twitter response to seeing his perpetual pec poses?)

But from one teen idol to another, Backstreet Boy Nick Carter is giving Bieber a bit of important advice — by defending his shirtless ways.

“When I was his age I had a little bit of a gut, so I couldn’t take my shirt of and take Instagram pictures,” Carter told Celebuzz. “More credit to Bieber, go for it!”

“I was really young at the time when we first started and going through my teenage years just having fun, being on stage, traveling the world and experiencing life in a whole different way than most people see it,” added Carter. “My perspective is exciting — you can do whatever you want.”

It’s been 20 years since we were all plastering our walls with The Backstreet Boys posters and memorabilia, but frontmen (Carter, A.J. McLean, Howie Dorough, Kevin Richardson, and Brian Litrell) still got it — paving the way for Bieber, One Direction and The Wanted.

After numerous chart-topping hits, a star on the Hollywood Walk of Fame and even a documentary on the way, the Boys have a lot to celebrate after two decades in the biz… and, Dorough admits, a lot they may want to forget.

“I spent more time in the mirror than my sister it was pretty sad,” Dorough said of his primping past. “Looking back going, okay, Puerto Rican and part Irish right there they should’ve told me that I shouldn’t have tried and grown out my hair that long. It was messed up and then I learned how to use products.”

Check out the video above for more on BSB’s look back at 20 years in showbiz — and Brian Litrell’s surprise (and silly) interview.