Poor, poor Nicolas Léonard Sadi Carnot. I mean, sure, we've all suffered through the equations for his theoretical heat engines in physics class. But the dude always gets snubbed by armchair and "professional" nutritionists alike when they start spouting off about calories. You can always tell they're experts on the subject, because invariably they walk up to a whiteboard and write a very scientific equation looking something like: Δ weight = calories in - calories out Of course, the somewhat more enlightened ones will be a bit more precise: Δ weight = calories consumed - calories burned They'll then go on to explain, in a very authoritative tone, how this is an irrefutable law of thermodynamics, and that a person can't lose weight unless he eats fewer calories than he burns, how this is all very well understood and accepted by all the top scientists, and so forth. And the onlookers all nod in agreement; I mean, after all, this seems so obvious - how ...