I found the sentence we've been looking for:
An hour of pushing a mop across the floor and wringing it out in a bucket works off 238 calories, the equivalent of a chocolate bar or two small glasses of wine.
But then what if what you were mopping up was wine, and the bucket you were wringing it into also had a tube hooked up to it that went into your mouth? An infinite loop. Until you had cleaned up all the wine on the floor, I guess, at which point you could just stand there, perfectly in balance.