APA Dictionary of Psychology

(symbol: MET) a unit of measurement of heat, or energy, produced by the body: 1 MET = 50 kcal/h/m² body surface. MET units are used to assess the expenditure of oxygen in a given activity; for example, 1 MET indicates that the body is at rest, 3 to 5 units would indicate light work, and more than 9 units indicates heavy work.