Comment Re:Hundred Push-Ups and other tools (Score 1) 201
Calories are just a concept.
While I agree with the majority of your post, this statement is completely false. A Calorie as used on a food label is a kilo-calorie, a unit of energy equal to 4184 joules. It is the energy that would be released by burning the food item in an internal combustion engine under ideal conditions (your body hardly does so under ideal conditions). That energy is then used to overcome friction and move things around (stuff you can figure out using what you learned in physics 1).
Also, obligatory xkcd: http://xkcd.com/435/