Jason Sudeikis Credits His Recent Weight Loss To Sex With Fiancé ...

Christopher Polk/Getty

Jason Sudeikis is looking much slimmer these days and he has his new fiancé, actress Olivia Wilde, to thank.

"The truth is, I'm not getting up an hour earlier and walking on a treadmill," Sudeikis reveals in the August issue of Elle magazine. "I have the greatest workout partner in the world. And you don't need a gym membership for that kind of workout."

The couple, who got engaged in January, have always been vocal about their active sex life.

"We have sex like Kenyan marathon runners," Wilde said last year, while Sudeikis told Elle, "I would say that's accurate."

Wilde has said that before she met Sudeikis, "I felt like my vagina died. It just turned off. Lights out."

Sudeikis continued to gush about his bride-to-be, saying "she's hilarious and kind and sweet."

When the magazine asked Sudeikis if there was a more masculine story he wanted to tell the public about himself than the one Wilde recently told about him falling out of a kayak, he responded, "What better story than meeting the girl of your dreams, sweeping her off her feet, and then being strong enough to carry her out? That's my story."

But it's not just Wilde who is responsible for the funny man's slim down.

"A lot of it comes from tiny things, like not eating barbecue sauce with my pizza at two in the morning," admits Sudeikis. "I think it's all a manifestation of being happy and wanting to treat myself well."

Here's Sudeikis showing off his svelte new frame at Spike TV's Guys Choice Awards last month:

Jason Merritt/Getty

And here he is at the ESPY Awards in 2010:

Jason Merritt/Getty

And with his former "Saturday Night Live" co-stars in 2009:

Charles Sykes/AP