Here's an excerpt from Vanity Fair's take on YC:
Today, Jason Shen is a different speaker, one who exudes confidence. As he approaches the dais, the former collegiate gymnast does a cartwheel. “I thought you guys need a little pick-me-up or something,” he says, and goes into his pitch. “Ridejoy is the community marketplace for rides. If you’re going on a trip, you can list extra seat space in your car. And if you need to get somewhere, you can find a ride using our site.” He explains that Ridejoy is adding an element of “reputation” to ride-sharing, a mechanism for payments, and a “great user experience.” Shen anticipates a question that may be in the minds of the audience members: “Maybe this is some kind of crazy San Francisco hipster thing. It’s not.”
I think you'll find that a lot of entrepreneurs work out. It has tremendous carryover benefits to confidence and social interactions like hustling startups.
Of course, being fit, in a good shape both physically and mentally are - always - indisputable advantages over those who lack such qualities. However, this completely misses the point that an attractive female has such a tremendous control over the social structure within the company that it alone is something no single man, regardless of how confident, how superior physically and mentally, can never have. Of course it's another question how a girl can take an advantage of this, if at all.
Maybe that's the reason?