I think it’s telling that you used the phrase “standards may be more forgiving” re: non-fit guys being into BBW. As a fit woman who has never been attracted to fit men, I think you are missing the “A” part in (F)FA pretty majorly. People who are attracted to BHMs and BBWs aren’t attracted because they’re “forgiving” - they’re attracted because a big man/woman makes their head spin, because a flirty encounter with a large barista makes their entire day, because rolls and chins and bellies make their pulse race. It’s not something they have much of a say in, the way you don’t have much of a say in who you are attracted to. It’s generally not related to how they view themselves - for instance, a very masculine presenting man who prefers very feminine presenting women usually doesn’t secretly try on his girlfriend’s makeup, nor does his girlfriend usually wish she could grow a beard. What we like in ourselves and what gets the blood racing can often be quite different.