New Study: Fatter Men Last ... Longer?

This week, I was reading one of my favorite sites — The Daily Beast (which, full disclosure, I've written for) — when I came across a startling headline: "Fat Men Last Longer in Bed."
I was immediately suspicious.
Title notwithstanding, the story is not exclusively about fat men, but is rather a compilation of fun facts about which kinds of people last longest, and why. But The Beast introduces it by saying: "Researchers in Turkey have finished a yearlong study that correlated body mass index with male sexual performance. Their findings may surprise you: Heavier men were able to make love for an average of 7.3 minutes, while slender men lasted an average of 108 seconds. The study, published in Nature, showed overweight men had higher levels of the female estradiol hormone, which blocks male hormones and delays the climax."
Slender men only last 108 seconds, on average? Whaaa? Not in my experience.
But then I read the fine print — and looked at the study The Beast referenced. I found that it was comparing obese men to a group of dudes who had problems with premature ejaculation, rather than comparing them to the male population at large. So, as far as I can tell, it's not that fatties last longer than all other guys — but rather that they last longer than premature ejaculators.
The rest of the piece was similarly disappointing; I was suspicious of nearly all the stats they listed. For instance, when I read, "Sixteen-to-24-year-olds last twice as long as people aged 55 and up," I thought, Nice! Scientific data that will help me to defend my perhaps unfortunate proclivity for dudes fresh out of college. (Even though — I know, I know — I have promised to swear off the Junior Mints.)
But after The Beast writer noted that she got the young-versus-old lovers stat from a Durex condom study, she went on to say, "Granted, the trouble with researching the durations of sexual encounters is that nearly all of the data is self-reported, which creates built-in problems with its accuracy." Isn't that the problem with just about ALL of the stats they mention? Because I can't imagine there are too many studies that involve volunteer lovers who allow researchers to tape sensors all over their bodies before observing them as they have laboratory sex.
So ... You tell me: Based on your observations, which lovers last longest?
I'll wager that it's the younger men ... and the ones who work out a lot. (Then again, I've never had sex with anyone who didn't fit into at least one of those two categories, if not both. So what do I know?)