Generation Iron - a sort-of sequel to the 1977 film Pumping Iron, narrated by Mickey Rourke and featuring cameos from that film's stars, Arnold Schwarzenegger and Lou Ferrigno - shows exactly what kind of dedication is needed to take out the title.
For Warren, that means a strict daily exercise regime that represents the amount of exercise an average person might do in a week. The 39-year-old admits it's a "crazy" sport to be part of.
Here's how Warren's day goes: He gets up at 6am, downs a coffee, then does "20 to 30 minutes of cardio" at home. He has breakfast, then heads to the gym for his proper workout: 90-odd minutes of hardcore weights, benches and presses.
He drinks a protein shake on the way home, then spends his afternoon eating four perfectly balanced, home-cooked meals, mostly consisting of chicken.
Warren will also cram in a 45- minute posing session - a workout in itself - as well as some tanning, and in the evening he'll do another 30 minutes of cardio.
He does this every day leading up to competitions. Warren doesn't eat out, hardly watches television and can't even remember what chocolate cake tastes like. That's why his biceps measure 58cm, his thighs 85cm and his chest a whopping 145cm.
But as Generation Iron shows, professional bodybuilding is a lonely, isolating and mentally draining sport that leaves precious little time for socialising, friends or family.
"Being a top-level bodybuilder makes you a very selfish, self-centred person," admits Warren.
"It's all about your training, your diet, your posing. It's all about getting you to your best."
Warren's best has seen him take out the Arnold Classic competition twice, in 2011 and 2012, but he's yet to win Mr Olympia - the world's top professional bodybuilding prize, which comes with a $250,000 winner's cheque - after six attempts. His best effort was second in 2009, but he says he's still got a few good years of competing left in him yet.
"I'm still hungry. Back in Arnold Schwarzenegger's day, if you were 30 you were considered old, but the guys are taking it to such a high level now in terms of muscle development. Compared to the 1970s, you really don't reach your peak until your mid-to-late 30s now. How long you can do it depends on the individual. There are some guys who are at the 40, 41, 42 mark still competing successfully."
Warren puts it down to improvements in knowledge about nutrition and supplementation. "I think nutrition is 70 per cent of it. Everyone thinks the training is key, and the training is obviously very important. You're not going to get big if you don't train, but you're not going to grow if you don't eat.
"I know guys who train really hard but they haven't made much progress over the years because their nutrition isn't good. Nutrition is key but, of course, it's the hard part, because if you can't have something you want it. It's just in your nature."
Warren isn't kidding when he says it's a "tough sport" that gets the better of many a competitor. "There's so much more to it behind the scenes than a lot of people think. Just to become a pro muscler, you're going to lose eight to 10 years of your life. Plus all the dieting and the training and the posing and the mental aspects. The cold, harsh reality of the life is that if you don't win, you don't have any money."
Then there's show day, which can see nerves overcome even the biggest of bodies. Mr Olympia competitors are judged on the sizes of various sets of muscles over a series of poses, and mind games play a big part between the athletes.
When asked how he handles them, Warren shows why he's considered one of the best in the business."Ain't no one going to psych me out, man. I've been in this thing too long. They can try but it ain't going to do them no good. I'm there to beat everybody who steps up on stage with me."
What: Generation Iron
Where: In cinemas from March 20
Also: Branch Warren will host a Q&A session at Generation Iron's Sylvia Park screening today from 6.30pm as well as making appearances at venues around the North Island. Check facebook.com for schedules.
Generation Iron Official Trailer (HD) Arnold Schwarzenegger, Mickey Rourke(1) from Flavorlab on Vimeo.
- TimeOut
