"It was definitely the hardest I'd worked fully and the best I understood a character and a world and a script and a story. That was the birth of the actor I am today."
And it was that exact character that helped Claflin to sympathise with women in the film industry who, he says, are regularly fat-shamed.
"I read in an interview recently and I think it's absolutely true: men have it just as bad," he said. "Well, not just as bad but they get it bad and it's never talked about.
"I remember doing one job when they literally made me pull my shirt up and were grabbing my fat and going 'you need to lose a bit of weight'. This other time they were slapping me. I felt like a piece of meat," he added.
Claflin starred as Finnick in two more of the Hunger Games movies in 2014 and 2015 and later starred in the 2016 movie Me Before You, where he was also required to look very fit.
"I'm not saying it's anywhere near as bad as what women go through but I, as an actor approaching each job, am insecure - especially when I have to take my top off in it - and so nervous. I get really worked up to the point where I spend hours and hours in the gym and not eating for weeks to achieve what I think they're going for," he told the SMH.
This isn't the first time the actor has spoken out against the ridiculous standards put on male actors to be in shape.
Claflin revealed he lost close to 20 kilograms in June last year to realistically portray his character Will in Me Before You, a fit businessman who becomes a quadriplegic after a motorbike accident.
"I had to get myself in peak physical condition to play Will before the accident, and that came along with at least one long and hard daily session in the gym and a very strict diet, with little sleep," he wrote.
In his recent interview with The Sydney Morning Herald, the 30-year-old actor added he believes these standards are something only recently placed on male actors.
"In the '50s and '60s, it was never an issue," he said. "James Bond never had a six pack. He had a hairy chest.
"Marlon Brando in A Streetcar Named Desire had an incredible body but he was by no means ripped to within an inch of his life. There's a filter on society that this is normal but actually it's anything but normal."
Claflin has two movies coming out this year. My Cousin Rachel, which also stars Rachel Weisz, is due in cinemas this month. Journey's End, starring Claflin and Asa Butterfield, is slated for release later this year.
