Katie Holmes proved that she has a sense of humour regarding her skinny frame, as she headed out for a day of filming on The Extra Man.

The actress - who is rumoured to be on a strict Scientology diet called the Purification Rundown - joked with reporters about her eating habits as she headed to the New York set of her upcoming movie.  

Katie said, "As you can see. I'm on my liquid diet right now."

That afternoon Tom's missus began shooting scenes at Stand - a neighbourhood burger bar - but not once did she indulge in a bite of food, according to the restaurant manager.

Peejay Bodoy told Life&Style, "I was shocked at how skinny she was.

"During the entire time she was here, I did not see her eat anything -- not a morsel. After five or so hours, I would have been famished!"

The actress recently sparked health fears over her apparent weight loss, which is said to be the result of a rigorous detox diet.

See Katie on set below