Noah Centineo has wowed fans by revealing a dramatic body transformation

The actor was photographed flexing his biceps and showing defined abs while wearing black sweatpants over bright pink underwear.

His long curly hair was tied back with a headband, and the selfie was taken in a modest room in Sydney, Australia, with a guitar visible on the bed behind him.

The post prompted a flood of comments from surprised fans.

One user wrote: "Did I miss a chapter??", while another added: "Grew his hair out. Bulked up. Whattttt we all missed the entire season?"

Others questioned his new look, with one writing: "This is not the Noah Centineo I remember."

Another asked: "Hold up a second....what???!!!....when did bro get so jacked??!!"

Anorther fan referenced his earlier character, saying: "I want Peter Kavinsky to be back!:("

Actress Rachel Zegler, 23, also commented on the photo, writing: "NOW HANG ON -."

Several fans speculated Noah's transformation is linked to his upcoming role as John Rambo in a Rambo prequel.

According to Deadline, the film is being developed by Millennium Media and will be directed by Jalmari Helander, 48, with production scheduled to begin in Thailand in early 2026.

Noah has previously starred in films such as The Perfect Date (2019) and the Netflix series The Recruit (2022), but he does not frequently update his Instagram, leaving the timeline of his physical change unclear.

His personal life has also drawn attention in recent months.

In March, Noah was seen leaving a Los Angeles restaurant with Zoë Kravitz, 36, sparking dating rumours. By May, Page Six reported the pair had enjoyed a brunch together at Chez Ma Tante, a café in Brooklyn's Greenpoint neighbourhood.

A source told the outlet: "I don't think they were showing too much PDA. They just tried to blend in and have a normal brunch."

Zoë has since been linked to Austin Butler, 34, and Harry Styles, 31, while previously calling off her engagement to Channing Tatum, 45, in late 2024.

Noah was earlier in a relationship with 28-year-old model Alexis Ren.