Bradley Cooper

Bradley Cooper

Bradley Cooper didn't wear underwear when he met US President Barack Obama.

The 'Silver Linings Playbook' actor and his girlfriend, Suki Waterhouse, met the US premiere at a state dinner last week, but he says gaining weight for a new role left him with no room for boxer shorts.

Speaking to talk show host Ellen DeGeneres, he said: "I'm prepping for new movie and I'm trying to gain weight fast, I've gained about 15 pounds in four weeks and nothing fits me anymore. I wore the tuxedo I wore to the Golden Globes and I just sort of threw it in the bag and went to Washington D.C.

"I'm getting dressed, like, 10 minutes before I was supposed to go and literally the pants go up to like here [halfway up his thigh].

"So I had to go commando because there was no room at all. I did. I had to... So it was really great. And you have to walk up the stairs and it was a nightmare. But I made it through."

Bradley, 39, is nominated for Best Supporting Actor for his role in 'American Hustle' at the Oscars on March 2 - his second year nominated for the award in a row - and is having trouble deciding between taking his sister and his mother with him, so appealed to Ellen, the awards' host, for help.

He explained: "I'm trying to take more than one person. My sister's coming from North Carolina ... How can I [choose?]. Maybe they'll sit them at the top, maybe there's some seats at the top?"

Ellen initially sounded doubtful, but later added: "I'll see what I can do for you."