Inside the Disney Channel’s brutal fame factory and how far Zac Efron, Demi Lovato and Selena Gomez really had to go to win roles: book

Zac Efron was not the obvious choice to star in “High School Musical,” the 2006 Disney Channel movie about a lovestruck basketball player who auditions for his school’s musical theater production. 

The then-17-year-old actor had a gap between his teeth. He had floppy hair. He was not a singer. He did not live in Los Angeles, but in the laidback college town of San Luis Obispo, in central California — a world away from Tinsel Town.

“He didn’t have any of that Hollywood polish at all,” casting director Natalie Hart tells author Ashley Spencer in the dishy new book, “Disney High: The Untold Story of the Rise and Fall of Disney Channel’s Tween Empire” (St. Martin’s Press, out now). “It’s sort of what endeared him to us, because he was just a good guy and a lovely kid.”

The “High School Musical” cast included Corbin Bleu (from left), Monique Coleman, Zac Efron, Vanessa Hudgens, Ashley Tisdale and Lucas Grabeel. Handout

But Disney Channel execs wanted a leading man with pearlier whites and a more “athletic build.”

Spencer writes that Efron jumped through all kinds of hoops to get the part. He underwent a makeover to fix his gap-toothed grin and mop of hair. Then he endured sessions in the recording booth laying down his vocals for the soundtrack — only to have his voice swapped out of the final film. 

“After everything was recorded, my voice was not on [the songs],” Efron told the Orlando Sentinel in 2007. “I was not really given an explanation.”

Efron was shocked, and hurt. He and his HSM peers “had all been cast as triple threats,” Spencer writes. “Now, Zac was the only one deemed unsuitable to fulfill his singing duties . . . [Disney had put him] in an incredibly awkward position.”

The Disney Channel debuted 1983 as a niche premium cable add-on aimed at families, but it didn’t develop into a tween powerhouse until the early 2000s. 

“High School Musical” star Corbin Bleu (right, with Efron) said the teen actors were treated like adults on set. “We were pushed to our max,” he recalled. Disney Enterprises