If you’re a fan of the show, you likely took immediate notice of the difference in his appearance and weight in Season 4 compared to previous seasons. “Many of you have asked about Hopper’s physical transformation from season 3 to season 4. My trainer @davidhigginslondon worked with me for 8months to make the transformation, and then another year to keep it through the pandemic,” he shared in the social media post alongside reference photos of his body from Season 1 versus the most recent season. “All told it was a difficult and exciting ride, changing diet and exercise plans (or lack thereof),” the actor added. The Hellboy star, 47, dropped over 75 pounds to film Season 4, in which Hopper is trapped in a Russian prison.  The extreme dedication to his career is apparent, as he divulged that even after losing all that weight, he has “recently ballooned up again” for a new role — Santa Claus in an upcoming holiday film. “I am struggling to fight back down towards a good weight for wherever Hopper ends up in season 5,” he said, confessing that “all this up and down is not good for the body, and I’ll have to give it up soon.” Following the influx of fan questions as a result of the social media post, the actor presented an informal Instagram Live with trainer David Higgins, where they spoke in-depth about his commitment to the lifestyle change and the methods in which he used to achieve the immense weight loss. During the course of the informational conversation, Higgins made sure to emphasize several times that he’s “not a doctor” and listeners should absolutely not take his medical advice. The actor continued to share what worked for him, attributing the weight loss to a mindset change, “pilates-based movement,” and prolonged intermittent fasting—a concept where you essentially decide a certain time period of each day you’ll consume appropriate portions of (healthy) food, versus hours of the day designated for not eating. Despite the associated health risks of such drastic and constant physical changes, Harbour said causing his weight to purposely fluctuate “is such a fun part of the job” because it allows him “to live in a different version of your skin for a while.” Season 4 of Stranger Things is currently streaming on Netflix! Season 5 has been confirmed as the final installment, but a premiere date has yet to be announced.  Next, We’ve Got New Intel on Stranger Things Season 4