It turns out that boobs not only move up and down but side to side and in figure of eights as well. (Husband pointed out that he's seen strippers do that and suggested slimming class should wear tassels and make a video.) When an average woman walks a metric mile her boobs travel 138m independently. Which led me to the conclusion that they must be using calories to do that so the bigger and bouncier the boobs the more calories used. (And thus more chocolate you can eat?)
However if you don't wear proper support, your Cooper's tendons get stretched and then you're headed for permanent boob droop. Too late for some of us I fear.
P.S. Is a metric mile different from a non-metric mile? Is there, in fact, such a thing as a metric mile? Surely it's a ... whatchamacallit?