Gadd, remembered for his role as a shy victim in Netflix's award-winning series "Baby Reindeer," will play a bully in a new series, for which he had to gain as much as 40 kilograms in just one year.

"In 'Baby Reindeer,' I weighed 69 kilograms, and in 'Half Man,' I weighed 109 kilograms. I really 'bulked up.' I feel like I'm dragging this huge body around. I feel heavier and bigger. What surprised me most about training was that I would always look and think: 'I'm not making progress, nothing's happening.' Then someone would see me and say: 'You're huge now,' but no matter how many times someone told me that, it never looked that way to me," Gadd said.

As he revealed to the media, such a transformation required absolute dedication. A year before filming, Gadd trained six times a week, sometimes twice a day, while simultaneously adjusting his diet to ensure muscle growth.

"I had a nutritionist and a trainer. In England, there was a company that sent meals, always rich in protein, no matter what. At the beginning, when I started training about a year before filming, maybe even longer, they were quite rich in carbohydrates. So, I would gain a lot of weight. We knew that lean mass wouldn't give me what I needed to look big. I never wanted it to be a wiry, steroid look," he added.

Gadd credits his trainer David Jenkins and nutritionist Andrew Roche for making his transformation journey easier.

His physical transformation was also noticed by fans, who commented on social media.

After Baby Reindeer, Richard Gadd worked out a lot to play Ruben in Half Man. pic.twitter.com/9h4lYiBNHG

By the way, Gadd is the creator and producer of the series "Half Man." The limited series is described as a story about two men who are not blood-related but are as close as they can be. One is fierce and loyal, and the other is mild-mannered.