James Corden has lost five stone and is the lightest he has been since he was a child.
Cuddly James has been a portly fellow for years but the star has been attempting to lose his excess pounds in a bid to win over US audiences.
The 33-year-old Bafta-winner is set to take his theatre hit One Man, Two Guvnors to Broadway and the star doesn't want to be judged for being overweight in America.
The History Boys actor, who jokingly describes himself as a "dancer" on his Twitter page, has a nine month old son and also wants to become more nimble so he can play with his boy.
The source said: "Since becoming a dad, his priorities have changed. He realised he wanted to get fit and maximise play time with his son Max.
"He didn't want to be huffing and puffing around after the youngster."
They added: "The final incentive was when his theatre hit One Man, Two Guvnors was signed up for a run on Broadway."
This isn't the first time the star has attempted to shift some weight and two years ago James enlisted the help of a personal trainer.
At the time, he said: "I've done nine sessions. I'm three weeks off bread, alcohol and potatoes. No beer - just Diet Coke now. I've ditched everything fun in life!"
However, James is apparently keeping to a simpler plan now and won't be going on the Dukan Diet any time soon.
The source said: "He’s not doing anything faddy but is simply trying to eat more healthily. The plan is to lose another stone-and-a-half by April, when the show kicks off in New York."
Good luck James!
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