Richard Gadd gained almost 100lbs before filming his new series Half Man.

The Baby Reindeer star plays Ruben in the hard-hitting new drama and explained that he bulked up for the part in a bid to "get away" from Donny Dunn, his alter ego in the award-winning 2024 Netflix show.

Richard told the How To Fail With Elizabeth Day podcast: "I knew in order for people to buy me as Ruben I needed to get away from Donny Dunn in almost every single way I could.

"I was 68.5 kg (151lbs) when I shot Baby Reindeer so I was rake thin and I intensely lost weight to do that. And I wanted to feel vulnerable in my body and slight. And I wanted to feel young and youthful in my body.

"So I knew I needed to do a 180 for Ruben and I was 110kg (242lbs) at my heaviest when I shot Half Man. So a huge, huge difference."

Gadd explained that his physical transformation was borne out of concern that audiences would struggle to see him beyond his part in Baby Reindeer.

The 36-year-old star - who has also written and created Half Man - said: "I needed to change everything. My size, my voice, my beard, my hairstyle, everything. I needed to transform.

"It's hard enough... If just your job as a sole actor on something (is) to kind of transform, but doing everything else alongside (is) obviously a huge commitment."

Richard also discussed how he gained weight for Half Man by following a dedicated training and nutrition programme.

The Scottish actor told Men's Health: "I had a nutritionist. I had a personal trainer. There was a company in England that would send meals up - it was always high protein, no matter what.

"And at the start, when I began training about a year out from filming, maybe even more, they were quite carb-heavy.

"So I would be gaining a lot. We knew that a lean bulk wasn't going to give me what I needed to look big. And I also wanted Ruben to look real. I never wanted it to be a veiny, steroid look."

Gadd credits his trainer David Jenkins and nutritionist Dr Andrew Usher for helping him "really, really bulk up".

The Emmy-winning star said: "Together they put me through my paces. They never let me slack off and always pushed me, and I'm always up for a challenge."