Body Composition and Gender of Children

Nearly from conception on, girls have more fat than-boys because girls have more estrogen. At puberty, when estrogen levels increase, so do fat levels. If girls do not have enough body fat, estro¬gen will drop and menstruation will cease until fat levels increase. Sometimes this happens with ath¬letes who are training; it is called secondary amen¬orrhea. In order to menstruate, girls and women need about 15 percent body fat (Sinning and Little 1987; Morrow, Jackson, Disch, and Mood 2000). Most girls have more than 15 percent fat. Obesity, or too much fat, begins at 20 percent for boys and 30 percent for girls (Morrow, et al. 2000). Approxi¬mately 1 in 4 children have too much fat; that is, they are obese based on percentage of body fat above 20 or 30 percent by gender. Girls are typi¬cally less active, which contributes to the higher percentage of body fat. The fact that girls are fat¬ter than boys can be blamed partially on biology but is attributable to environment (Thomas and French 1985). Gaining fat is easier for girls, thanks to estrogen, and encouraged in girls by socio cul¬tural norms, which suggest that girls should be less active than boys. Physical activity can facili¬tate weight control and healthy growth. This is an important fact to present to girls and boys.