Zac Efron abs-olutely beefed up for those teeny red shorts.
On the set of the 2017 Baywatch reboot, the We Are Your Friends star is "channeling his energy into working out," a source exclusively reveals in the latest issue of Us Weekly.
"He is so regimented about everything he does," the insider tells Us of the 28-year-old actor, who will play lifeguard Matt Brody in the upcoming flick.
One trick Efron, who entered rehab for alcoholism in 2013, uses for a more chiseled appearance on camera is a common bodybuilder technique called "flushing." The source explains: "Before they shoot a big shirtless sequence, Zac won't have any water for 12 hours to make his muscles look as defined as humanly possible."
Scenes with Efron's costar Dwayne "The Rock" Johnson are jacking up the pressure. Adds the pal, "Zac jokes that he doesn't want to look tiny next to The Rock."
However, the competition seems to be in good fun. "Special delivery for The Rock," Efron captioned a March 15 shirtless Instagram shot in which he looked incredibly ripped on the Florida movie set.
On February 22, after his first day on set, Efron captioned a snap with the retired pro wrestler, 43: "First day protecting the bay is a wrap. More adventures lie ahead."
Baywatch is scheduled to be released in 2017.
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!