4. Maintenance energy need is related to body size and composition

Studies of adult women and adolescent girls of widely varying body size show that energy requirement bears a direct, and linear, relationship to body weight, to lean body mass, and to body fat content (FORBES, 1989). The calculated regression slopes for adult women average 18 kcal per kg weight, 51 kcal per kg LBM, and 23 kcal per kg fat. Thus, a woman weighing 61 kg needs 18 kcal more each day to maintain her weight than one who weighs 60 kg. Values for adolescent girls are slightly higher, due presumably to greater physical activity and the requirement for growth. Multiple regression analysis shows that LBM exerts a greater influence on energy need than does body fat. Other investigators have found that basal metabolic rate bears a closer relationship to LBM than to body weight.