[Uberphallus]

Yeah, if you train a model with pictures of the same person, or maybe their family, you may be able to guess the BMI from the face, after all, the face stores fat in a non linear way.

But I remember back in college a friend was severely overweight and eventually he was motivated to lose weight. Diet and exercise details aside, in a couple of years he became a BMI 28, but very low fat, ripped and chiseled muscled up individual. But interestingly, he mostly kept his fat person face, those cheeks, while they shrank, weren't going away.