Bradley Cooper picked the worst time to make a foodie movie when he started work on Burnt, because he was trying to lose weight for The Elephant Man.

The American Sniper star admits it was tough being around scrumptious food while he was trying to shed 40 pounds (18.1 kilograms) for the play.

"The food on set was unbelievable," he tells WENN. "We were cooking and the way they set it up was (real-life chef) Marcus Wareing created the dishes and then we would have recipes.

"All the other cooks were not extra actors; they were cooks that work in Michelin star restaurants around London. We were cooking the food, so we were eating the food. In between takes we would eat a lot of the meat.

"I was trying to lose 40 pounds, so it was kind of a nightmare to do a cooking movie in between. You'll see scenes in the movie where my face is two inches wider than other times because we shot out of sequence."

But Cooper wouldn't have missed the chance to work alongside Wareing, the owner of one of London's top restaurants.

He admits the masterchef and his team turned him into an oyster shucker.

"I shucked 60 oysters," the actor laughs. "There's no double in the whole movie. In fact they did this thing where the guy loosened about 10 of them but we got through them in seconds. I had this stupid idea that I'd bring the bag of oysters, which wasn't pre-shucked. That was the first day of shooting.

"If you're ever gonna slice your hand, it's shucking an oyster. I even said to (director) John Wells, 'Bro, just to let you know, if this goes south you better find a lot of other stuff to shoot!'"

In the film, Cooper plays a fallen chef attempting to rebuild his reputation.