Changes in body composition in adolescent boys

Changes in body composition were studied at age 10 and 13 years in 47 healthy school children of the Glasgow area. When seen at age 13, 22 had reached a total puberty rating (TPR) greater than 4 while the other 25 had a TPR less than 4. On relating body composition at age 10 with that observed at age 13 for the earlier maturing and later maturing boys it is clear that during this age period there are very fast and dynamic changes in body composition that can be characterized as a 'fat-wave' where children gain weight on a tissue that is almost 40 per cent fat, followed by the 'growth spurt' where they gain tissue that is almost 100 per cent lean mass while using up some of their body fat. Knowledge of this event is of importance for interpreting nutrition and body composition data in this age group especially when inter-social or inter-ethnic comparisons are being made. Some case observations suggest that the magnitude and direction of these changes in body composition can be influenced by environmental modulators, especially diet and physical activity.