I'm a fatty..
Also my theory on why cyclists are fat: too little, too late. You can't reverse the work of time.
Also, it's a safe haven for white people (yes, Tour de France..notice how the peleton looks pretty damn white in the sunlight)
it's a sport where throwing $$$($)^$$$ at your bike can compensate for your poor performance (it has to be fast if it looks fast right?)
What else: in other sports, fat people better check themselves before they wreck themselves. (if a fat person ran/jogged was as devoted as they were to cycling, they would be looking at knee replacement surgery faster then the Douglas X-3.