The actor tried to fatten himself up for a new screen role.
Benedict Cumberbatch had to load up on fattening treats to get in correct shape for his latest project.
The actor was ''force-feeding himself Doughnuts'' to put on weight in order to play his character in 'Parade's End'.
His director in the BBC Two drama, Susanna White, revealed that he made the decision to pile on the pounds as novelist Ford Madox Ford described his character as fat.
She said: ''He was tired, having just come off the set of 'Sherlock'.''
She added that he was ''force-feeding himself Doughnuts'' to fit the image.
Meanwhile Susan said that, when she started filming the series, she was conscious of ''one American actor'' who was proving troublesome.
She admitted: ''He was distracting The Others, joking. I took him to my trailer and told him: 'You are off my set if you behave like that.' He thanked me for doing it like that. He never misbehaved again.''
Benedict had to ''pinch himself'' to believe his luck when working on 'Parade's End'.
The 'Sherlock Holmes' actor - who recently made a jump into films, appearing in 'War Horse' and filming a role in the eagerly anticipated 'Star Trek' sequel - was shocked he had the opportunity to play Christopher Tietjens in the BBC adaptation of the book because he got to work with Rebecca Hall.
He said: ''I have never worked opposite an actress who has such an extraordinary command of her character. She is mesmerising to watch. And we have been friends for 10 years. Having her on set was another reason to pinch myself that I'm paid to do this.''