Having a larger body mass index (BMI), that is.
Sex researchers at Ecriyes University in Turkey did a year-long study documenting the correlation between BMI and male sex performance. In a nutshell, heavier guys last longer. Heavier guys last an average of 7.3 minutes during coitus, while thin guys last only about 108 seconds.
Hopefully, those 7.3 minutes are performed cowgirl-style!
Anyway, maybe thin guys need to ramp up that foreplay, eh?