Ehhhh, I'm 6ft tall and start looking pretty auschwitz-mode at around BMI 18.5 Right now I hover at BMI 20, since holidays (I like to stay at BMI 19 because I like the thin look). At 18.5 and below, I am much thinner looking than the VS models, and you can see all of my ribs without me sucking it in. I'd estimate their BMIs to be 19.5-21, depending on muscle mass.