To me, weight has little (if anything) to do with fat. If you look good and you're proportional, you're not fat. Some like to see ribs, some like to grab a handful of something. I like petite, shorter than me (let's say 5'4" for her). However, some of the sexiest women I've known were 5'10" and 180, but well fit.
Even a petite girl can wear a thong that's too tight, and the flesh hanging over the strap is a turnoff to me. Same girl in the right size thong is awesome.
I think I'm fat, but when I tell most women that they say I'm crazy (okay, most are dancers/providers and want my money, but most have known me long enough to know that I appreciate honesty & can take it). That's the standard I hold for myself, and they are comparing me to the average guy.
If your rolls have rolls, you are fat (not BBW).