Your gift recipient: Loves to burn that fat, baby.

Yeah, but: Do they know how much fat they’re burning, though?

This oblong white box about the size of a Bluetooth speaker can track your level of ketosis—the metabolic process by which your body burns fat—using your breath. You exhale into an inhaler-like mouthpiece and drop it in the device, and a few seconds later, this thing spits back a quantified measurement of just how hard your body is working on your New Year’s resolution. No, it isn’t cheap, but if you think of it as adding $58 and change to your monthly gym membership for the ability to tell whether what you’re doing with that gym membership is actually making a difference, that price tag suddenly isn’t (quite as) bad.

LEVLhome device, $699, buy now at