The amount of energy required by the body for normal function, growth, repair, and physical activity. Daily calorie requirements vary from person to person and depend largely on how active an individual is. To maintain health, sedentary women and older people must take in about 1,600 calories a day. Active women, children, teenage girls, and sedentary men require approximately 2,200 calories. Very active women, teenage boys, and active men need about 2,800 calories daily.