I wonder how much of that shift is due to cultural changes since then, but also how much was just the "bit" that he was playing up how "fat" he was. It's probably a hefty amount (hehe) of both, bc regardless of the general population, the media itself at one point avoided thicker people.
It's a matter of perspective and confidence ... when Chris Farley does it, it's sexy and funny ... I'm not as pudgy as Chris but if I did that, I would look disturbing and even frightening.