'Dancing With the Stars': Backstreet Boys' AJ McLean Reportedly Joining Season 29

AJ McLean is getting ready to rock his body on the ballroom floor as the Backstreet Boys alum joins Dancing With the Stars, Entertainment Tonight reported Monday. Sources confirmed to the outlet that the former boy band-er is set to appear on Season 29 of the ABC dance competition show, which premieres Monday, Sept. 14.

The only confirmed member of the Dancing With the Stars' celebrity line-up is former Bachelorette Kaitlyn Bristowe, who was announced as the first member of the cast back in June, but McLean teased his "big news" via Instagram on Monday, showing off some major changes to his diet and exercise routine he has made recently. Converting to a "very strict" grain-free, gluten-free, sugar-free and sober way of living for the past nine months, McLean thanked his trainer for playing a role in his "transformation," and getting him prepared for "what's to come in the next few weeks."

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"A lot of surprises coming from me," he teased. "I can't tell you guys exactly what yet but I'm doing this for two reasons: one, to get in the best shape of my life, and to be healthy and to be happy, physically, mentally, and emotionally, and there's something else coming up. Can't tell you what it is but believe me you'll know why based on that."

The full casting announcement will be revealed on Wednesday, Sept. 2 on Good Morning America. Until then, the only line-up fans have confirmed for them is the list of pros: Sasha Farber, Pasha Pashkov, Jenna Johnson, Emma Slater, Brandon Armstrong, Alan Bersten, Val Chmerkovskiy, Peta Murgatroyd, Gleb Savchenko, Cheryl Burke and Keo Motsepe. After a one-season break that followed her Season 27 win alongside Bobby Bones, Sharna Burgess will also be back for another go at the Mirrorball Trophy, as will Artem Chigvintsev, who was announced Monday as the 15th and final pro to join the show after also sitting out Season 28. There are also two new pros for fans to root for this season — Britt Stewart, the first Black female pro and former troupe member, and Daniella Karagach, former troupe member and wife to Pashkov.

Season 29 of Dancing With the Stars will be the first since longtime hosts Tom Bergeron and Erin Andrews were replaced by Tyra Banks. Bergeron broke the news that he had been fired on social media last month, and ABC followed up shortly with a statement confirming that DWTS was shaking up the hosting role altogether, also ending Andrews' time on the show.