Aerobic vs. Anaerobic. To understand the relationship between weights and calories, you need to know the difference between aerobic and anaerobic exercise. Sustained aerobic exercise, like steady jogging or cycling, is low intensity and can thus be done for a longer period of time.
absolute advantage. In the theory of international trade, a country or firm has an absolute advantage if it can produce a product (good or service) more 'efficiently' (cheaply) than others. First suggested by the UK economist Adam Smith (1723-90) as an extension of his division of labor doctrine. See also absolute cost advantage and competitive advantage.
David Ricardo, the British economist who invented the theory of comparative advantage in 1817, actually knew about this problem perfectly well, and wrote about it in his book on the subject. So there's no excuse for modern economists to ignore it. Dubious Assumption #6: Short-term efficiency causes long-term growth.