Inside Bradley Cooper's brutal 6,000 calorie diet for American Sniper

Bradley Cooper has gone to great lengths to hone his craft, having dedicated six years learning to conduct for his role in Maestro, and worked with a dialect coach for months to lower his speaking voice by an octave while appearing in A Star is Born.

At the 87th Academy Awards, the actor scored a Best Actor nod for his role as former Navy seal Chris Kyle in Clint Eastwood’s American Sniper.

The film, based on the military man’s novel of the same name, follows the life of the deadliest marksman in US military history, and stars Sienna Miller, Luke Grimes, and Jake McDorman in supporting roles.

In a recent interview, Cooper, 51, revealed he gained 24kg in less than six months by training in the gym and taking his nutrition seriously.

Bradley Cooper put on 24kg of weight to accurately portray Chris Kyle in American Sniper (Warner Bros.)

“I couldn’t do anything that would ever achieve what he achieved,” he recently told Joe Rogan on his podcast, “but it was like, what can I do to look like a master?”

First, the Marvel favourite was instructed to eat a whopping 6,000 calories per day.

The NHS advises that the average man needs around 2,500kcal a day - meaning Cooper was eating almost 2.5 times that.

He initially tried to hit the intense calorie goal by eating whole foods but eventually gave up. He instead decided to split roughly half of his daily intake into protein shakes.

The actor spoke about his diet in a new interview (The Joe Rogan Experience podcast/YouTube)

This was because Cooper’s body physically couldn’t process that much food, leaving him in pain and discomfort, the US celebrity admitted.

“I remember the first week, I had an incredible chef, and I couldn’t move. I couldn’t even move my stomach,” he lamented.

In 2015, Cooper revealed he also ate energy bars during this bulking phase, and that putting weight on ‘changed’ the way he walked.

“If someone bumps into you on the sidewalk, they kind of ricochet off. You go to a party and everyone’s dancing, you’re not being moved by anybody,” he told Men’s Health at the time.

The star consumed 6,000 calories per day to reach his goal (Warner Bros.)

As well as eating a large volume of food, the father-of-one was written onto a gruelling gym regime.

While working with celebrity trainer Jason Walsh, who has also trained Brie Larson, Jake Gyllenhaal, Pedro Pascal, Cooper was told to focus on strength training.

“I had three rest days. No cardio. It was all strength training, and it was all focused around deadlifting.

On Monday and Tuesday, he would complete his first session at 5.30am before heading back to the gym at 3.30pm or 4.30pm.

Wednesday would be a rest day before the routine started again on Thursday and Friday.

The three-time Grammy winner would also be instructed to rest again on the weekend.

Cooper’s latest film, Is This Thing On? - which he directed - is in cinemas now. According to IMDB, he has two confirmed jobs in the works: an untitled Margot Robbie Ocean’s Eleven film, and an untitled Frank Bullitt project.