Energy expenditure is dependent on a person's sex, metabolic rate, body-mass composition, the thermic effects of food, and activity level. The approximate energy expenditure of a man lying in bed is \(1.0\,kilo\,calorie\,per\,hour\,per\,kilogram\). For slow walking (just over two miles per hour), \(3.0\,kilo\,calorie\,per\,hour\,per\,kilogram\). For fast steady running (about 10 miles per hour), \(16.3\,kilo\,calorie\,per\,hour\,per\,kilogram\).
Females expend about 10 per cent less energy than males of the same size doing a comparable activity. For people weighing the same, individuals with a high percentage of body fat usually expend less energy than lean people, because fat is not as metabolically active as muscle.