Zac Efron on set filming 'AT&T's Life, Gig-ified' event on January 7, 2022 in Santa Clarita, California. (Photo by Joe Scarnici/Getty Images for AT&T)

Zac Efron is explaining the truth behind “Jaw-gate.” The controversy began last April after fans noticed that the High School Musical alum looked drastically different when he appeared in an Earth Day PSA. Fans suspected he’d had plastic surgery of some kind.

During an interview with Men’s Health published Wednesday (September 7), Efron, 34, was asked about the speculation that he had work don on his jaw. He explained that his looks changed after he fell over at his home and broke his jaw in November 2013. Due to complications from his injuries, his face and jaw muscles have had to work extra hard.

Efron explained that the masseter muscles, used for chewing, work together with the other muscles of the face “like a symphony.” When he was injured, the muscles on the inside of his face and jaw had to compensate. As a result, he began working with a specialist. He still does physical therapy to mediate this. However, he stopped briefly while in Australia to film season 2 of his Netflix series Down to Earth. “The masseters just grew,” he says. “They just got really, really big.” And that is what accounts for his somewhat different appearance.

The Greatest Beer Run Ever star says he didn’t know that “Jaw-gate” was a thing, until his mother called to ask if he’d gotten plastic surgery. The actor says this is because he generally avoids social media. This is a survival tactic that he has been honing since he became a public figure at 17 years old. “If I valued what other people thought of me to the extent that they may think I do. I definitely wouldn’t be able to do this work.”

Elsewhere in the interview, Efron also opened up about the struggles he experienced while filming his new movie. “I started to develop insomnia,” he says, adding that he fell into a “pretty bad depression, for a long time. Something about that experience burned me out. I had a really hard time recentering. Ultimately they chalked it up to taking way too many diuretics [for Baywatch] for way too long, and it messed something up.” Six months after the film wrapped, he finally began to feel right again.

The Greatest Beer Run Ever releases in theaters on September 30.