Technically, circumference is a 1D measurement. Waist circumference is a good metric for a different reason, because belly fat is the most dangerous type of fa

Technically, circumference is a 1D measurement. Waist circumference is a good metric for a different reason, because belly fat is the most dangerous type of fat (specifically visceral fat, which is stored between the inner organs and next to impossible to measure without lab-grade equipment, but the idea is that it correlates with circumference). Never heard of a fat tax, but it sounds dystopian.