Still seems like a definitional problem, with an imprecise meaning behind the word "skinny."

Even according to BMI, she’s bordering on underweight.

Bordering on, but still on the "normal" side of the chart.

Does "skinny" look to broad population averages, or celebrity averages, or even celebrity averages for that particular age, or some kind of ideal? Is "skinny" a pejorative, negatively loaded term?

I wouldn't call Taylor Swift "skinny" if that's intended to mean thinner than ideal. But she is thinner than the American average. Is the American average considered "fat"? How much of a gap is there between skinny and fat, occupied by people who are neither?