You've probably heard of hydrostatic weighing, where the amount of water your body displaces while submerged reveals how much of you is lean meat and how much is flab. The Bod Pod takes that concept a step further, using air instead of water to see what you're really made of. It measures mass and volume, and from that it can extrapolate your whole-body density.
Even though the Bod Pod, a fiberglass chamber, has a nice big picture window up front, it still must not be much fun for the claustrophobic. But it only takes five minutes to complete the procedure, it's noninvasive, and it can be used to weigh even the biggest bruisers—500-pounders can fit into the thing.