You can be a shirtless, badass, 300 Spartan warrior cosplayer even if you're not in shape. You just need a lot of paint and someone with some art skills who isn't afraid to touch your chubby belly.
The photos you see hear are of Mr. Nagata from Japanese comedy site Omocoro, and he had an artist named Hikaru Cho come in to paint his chiseled Spartan body. The process took over three hours to complete, and it looks like Nagata even got himself a haircut.
It's amazing what you can do with a little shading on the body. I thought this was so funny. Thanks to Kotaku of the heads up.