Director Judd Apatow was once convinced to adopt a vegetarian diet after listening to arguments laid out by actor and animal rights activist James Cromwell during a radio interview.

The Knocked Up filmmaker reveals Babe star Cromwell, who regularly fronts hard-hitting campaigns for People for the Ethical Treatment of Animals (Peta), explained his points of view so well, Apatow decided to give up eating meat - but he only lasted 12 months.

He explains, "I tried to be vegetarian for a year and I gained a lot of weight because I said, 'You know what? I'm going to replace all meat with pizza.' And I gained so much weight...

"I was listening to the radio and James Cromwell was on the radio... and he was explaining why you should be a vegetarian, the philosophical and ethical reasons and environmental reasons, and the second he was done talking, I couldn't eat meat for a year, and then I just got so bored of leaves, but I'll probably do it again at some point."

Cromwell became a vegetarian in 1974 after a visit to an abattoir in Texas.