David Harbour, 'Stranger Things' star, Posts Before-and-After Pics of 75-Pound Weight Loss Journey

David Harbour shared new photos documenting his weight loss journey for season four of "Stranger Things," revealing he lost 75 pounds for his role as Jim Hopper.

Harbour wrote in an Instagram post Thursday he worked with a personal trainer for eight months to make the transformation, and for another year to "keep it through the pandemic."

"All told it was a difficult and exciting ride, changing diet and exercise plans (or lack thereof)," Harbour said.

Harbour shared side-by-side shirtless photos of his character in season three and and season four, as he responded to fans asking about Hopper's physical transformation between the two seasons.

The 47-year-old actor also shared a mirror selfie from shoot day of the season four finale, adding "the black x's are for cgi scarring because of the problems with the practical effect."

Hopper, the town of Hawkins' police chief, was taken to a Russian prison facility after the season three finale, where he was tortured by Russian government officials. A scene in the fourth season shows Hopper shirtless, where he is covered in scars and underweight.

All told, Harbour said he dropped from about 265 or 270 pounds "all the way down" to 190 pounds.

Harbour also revealed in the post he had to gain most of the weight back to star as Santa Claus in the upcoming Christmas thriller "Violent Night."

"Recently ballooned up again to play jolly ole St. Nick in a flick I can’t wait for you to see this holiday season, so I am struggling to fight back down towards a good weight for wherever Hopper ends up in season five," Harbour said.

"All this up and down is not good for the body, and I’ll have to give it up soon, but it is such a fun part of the job to live in a different version of your skin for a while."

Harbour is set to reprise his role as Hopper in season five — the show's final season — though it's not clear when it will be coming out. Matt Duffer, the show's co-creator, told TVLine last month the show doesn't have a start date for shooting.

But Harbour told GQ earlier this month he predicted the finale could come out by mid-2024, "based on our track record."