James Franco. Picture: Reuters/Mario Anzuoni

Hollywood actor James Franco has revealed he ate salads for "a year and a half" to prepare for sex scenes in 'The Disaster Artist'.

The 39-year-old actor stars as the Polish-American filmmaker Tommy Wiseau in the biographical comedy-drama movie, and James has revealed just how seriously he took his pre-shoot preparations.

He shared: "I ate a lot of salads. Like, a year and a half of salads for lunch and dinner.

"Speaking of sex scenes, he has some infamous sex scenes.

"[Wiseau is] unnaturally cut [and] he's incredibly pale. He looks like a muscular corpse."

James' preparations also helped him with his starring role in the HBO TV series 'The Deuce', which centres on the rise of the porn industry in New York City in the 70s.

In the show, James plays twins brothers Vincent Martino and Frankie Martino, and the Hollywood star needed to be in shape in order to fit into the skin-tight attire he was required to wear.

Speaking to 'Entertainment Tonight', he explained: "I had to depict the making of those scenes, so I started the salads for that and then it just rolled into this and I was like, 'All right, I'll keep it up for the 70's clothes.'"

And despite the X-rated nature of sex scenes, James insisted the cast always approached them with the utmost professionalism.

He said: "The truth is, you want to be really professional in those things.

"No goofy rituals, it's [just] business, everybody up front and honest with each other."

Last month, meanwhile, James admitted he is "addicted" to his work.

The actor - who has previously admitted to dabbling in drugs and alcohol - revealed he is a complete workaholic.

He said: "The thing about work addiction is our culture supports it. We reward hard work and success. But it can really mask addictive, escapist behaviour. Every interview I gave, people would tell me, 'You're known for doing all these things, are you a workaholic?' And what I would hear was, 'That means you work really hard. You work harder than anybody.'

"The curse of that is that I actually couldn't enjoy my success. I was nominated for an Oscar, I was working with all my heroes. All the dreams I'd had as a young man had come true. And I still couldn't enjoy it. It was never going to be enough."