I don't buy the "metabolism excuse" and it's been overused and abused!
I was in San Francisco earlier this year, I remember seeing families of tourists and tell right away if they were Americans or Europeans without having to listen to them talk. The American families always had 1 or 2 members overweight.
We didn't have this problem before, 40 years ago the world mocked Americans for many things (real or untrue) but not for being overweight. If you are in a big city where folks take public transportation or just walk, you won't find such a high percentage of obese folks and specially children like you do in places where public transportation doesn't exist. Lifestyle matters!
Plenty of guys are chubby chasers or want to try it because they find it kinky, nobody argues that, and we take your word as valid just like so many other forum frequent posters who constantly have free sex with men who are in shape.
In jails most straight men prefer to fuck out of shape men because they find their body type more appealing and closer to a woman's soft body. Surprisingly there are not many overweight escorts or even porno where all or some of the performers are obese. I'm sure if Men.com or Falcon were to film a video with an overweight performer it will be a hit, and some might try it in real life.