Liam Hemsworth can't compete with Miley Cyrus' dancing skills.

The Australian actor admits his girlfriend completely shows him up with her moves on the dancefloor so doesn't even try to keep up.

Liam - who met Miley on the set of their movie 'The Last Song' - said: "She does a lot of dancing - that's her work-out. I'm a terrible dancer. I couldn't keep up with her dancing because she's super flexible and she's throwing up her legs up around her head and stuff like that."

Instead Liam says he surfs to keep fit as he finds going to gyms "boring".

He told People.com: "Surfing has been my main sport growing up, so that's always helped. It feels like it's the most boring thing, sitting on the treadmill or on a bike. It just explodes my mind!"

Liam, 20, has to exercise even more now he spends a lot of time in America because he's eating more junk food.

He said: "The hamburgers in America are the best in the world. Mel's Diner in Los Angeles - they are my favourite hamburgers. I could eat there every day. They are ridiculous."